diff --git a/hmm.json b/hmm.json
index 50cc68851..f06b295e4 100644
--- a/hmm.json
+++ b/hmm.json
@@ -49,8 +49,8 @@
       "name": "haxeui-core",
       "type": "git",
       "dir": null,
-      "ref": "f5daafe93bdfa957538f199294a54e0476c805b7",
-      "url": "https://github.com/haxeui/haxeui-core/"
+      "ref": "e92d5cfac847943fac84696b103670d55c2c774f",
+      "url": "https://github.com/haxeui/haxeui-core"
     },
     {
       "name": "haxeui-flixel",
diff --git a/source/funkin/Conductor.hx b/source/funkin/Conductor.hx
index 9bd668b69..b0ad6c221 100644
--- a/source/funkin/Conductor.hx
+++ b/source/funkin/Conductor.hx
@@ -47,7 +47,7 @@ class Conductor
   /**
    * Beats per minute of the current song at the current time.
    */
-  public static var bpm(get, null):Float;
+  public static var bpm(get, never):Float;
 
   static function get_bpm():Float
   {
@@ -67,7 +67,7 @@ class Conductor
   /**
    * Duration of a measure in milliseconds. Calculated based on bpm.
    */
-  public static var measureLengthMs(get, null):Float;
+  public static var measureLengthMs(get, never):Float;
 
   static function get_measureLengthMs():Float
   {
@@ -77,7 +77,7 @@ class Conductor
   /**
    * Duration of a beat (quarter note) in milliseconds. Calculated based on bpm.
    */
-  public static var beatLengthMs(get, null):Float;
+  public static var beatLengthMs(get, never):Float;
 
   static function get_beatLengthMs():Float
   {
@@ -88,14 +88,14 @@ class Conductor
   /**
    * Duration of a step (sixtennth note) in milliseconds. Calculated based on bpm.
    */
-  public static var stepLengthMs(get, null):Float;
+  public static var stepLengthMs(get, never):Float;
 
   static function get_stepLengthMs():Float
   {
     return beatLengthMs / timeSignatureNumerator;
   }
 
-  public static var timeSignatureNumerator(get, null):Int;
+  public static var timeSignatureNumerator(get, never):Int;
 
   static function get_timeSignatureNumerator():Int
   {
@@ -104,7 +104,7 @@ class Conductor
     return currentTimeChange.timeSignatureNum;
   }
 
-  public static var timeSignatureDenominator(get, null):Int;
+  public static var timeSignatureDenominator(get, never):Int;
 
   static function get_timeSignatureDenominator():Int
   {
@@ -151,7 +151,7 @@ class Conductor
   public static var audioOffset:Float = 0;
   public static var offset:Float = 0;
 
-  public static var beatsPerMeasure(get, null):Float;
+  public static var beatsPerMeasure(get, never):Float;
 
   static function get_beatsPerMeasure():Float
   {
@@ -159,7 +159,7 @@ class Conductor
     return stepsPerMeasure / Constants.STEPS_PER_BEAT;
   }
 
-  public static var stepsPerMeasure(get, null):Int;
+  public static var stepsPerMeasure(get, never):Int;
 
   static function get_stepsPerMeasure():Int
   {
diff --git a/source/funkin/input/TurboKeyHandler.hx b/source/funkin/input/TurboKeyHandler.hx
index 3719ff7cc..099d373b4 100644
--- a/source/funkin/input/TurboKeyHandler.hx
+++ b/source/funkin/input/TurboKeyHandler.hx
@@ -26,7 +26,7 @@ class TurboKeyHandler extends FlxBasic
   /**
    * Whether all of the keys for this handler are pressed.
    */
-  public var allPressed(get, null):Bool;
+  public var allPressed(get, never):Bool;
 
   /**
    * Whether all of the keys for this handler are activated,
diff --git a/source/funkin/play/PlayState.hx b/source/funkin/play/PlayState.hx
index ed82d6e99..068f32f97 100644
--- a/source/funkin/play/PlayState.hx
+++ b/source/funkin/play/PlayState.hx
@@ -251,14 +251,14 @@ class PlayState extends MusicBeatSubState
 
   var overrideMusic:Bool = false;
 
-  public var isSubState(get, null):Bool;
+  public var isSubState(get, never):Bool;
 
   function get_isSubState():Bool
   {
     return this._parentState != null;
   }
 
-  public var isChartingMode(get, null):Bool;
+  public var isChartingMode(get, never):Bool;
 
   function get_isChartingMode():Bool
   {
@@ -427,7 +427,7 @@ class PlayState extends MusicBeatSubState
    * Data for the current difficulty for the current song.
    * Includes chart data, scroll speed, and other information.
    */
-  public var currentChart(get, null):SongDifficulty;
+  public var currentChart(get, never):SongDifficulty;
 
   function get_currentChart():SongDifficulty
   {
@@ -439,7 +439,7 @@ class PlayState extends MusicBeatSubState
    * The internal ID of the currently active Stage.
    * Used to retrieve the data required to build the `currentStage`.
    */
-  public var currentStageId(get, null):String;
+  public var currentStageId(get, never):String;
 
   function get_currentStageId():String
   {
diff --git a/source/funkin/play/character/BaseCharacter.hx b/source/funkin/play/character/BaseCharacter.hx
index c7b58c393..30b549fd3 100644
--- a/source/funkin/play/character/BaseCharacter.hx
+++ b/source/funkin/play/character/BaseCharacter.hx
@@ -66,7 +66,7 @@ class BaseCharacter extends Bopper
    * The offset between the corner of the sprite and the origin of the sprite (at the character's feet).
    * cornerPosition = stageData - characterOrigin
    */
-  public var characterOrigin(get, null):FlxPoint;
+  public var characterOrigin(get, never):FlxPoint;
 
   function get_characterOrigin():FlxPoint
   {
@@ -103,7 +103,7 @@ class BaseCharacter extends Bopper
   /**
    * The absolute position of the character's feet, at the bottom-center of the sprite.
    */
-  public var feetPosition(get, null):FlxPoint;
+  public var feetPosition(get, never):FlxPoint;
 
   function get_feetPosition():FlxPoint
   {
@@ -264,7 +264,7 @@ class BaseCharacter extends Bopper
   /**
    * The per-character camera offset.
    */
-  var characterCameraOffsets(get, null):Array<Float>;
+  var characterCameraOffsets(get, never):Array<Float>;
 
   function get_characterCameraOffsets():Array<Float>
   {
diff --git a/source/funkin/play/cutscene/dialogue/Conversation.hx b/source/funkin/play/cutscene/dialogue/Conversation.hx
index a6851f0f9..2b7db381c 100644
--- a/source/funkin/play/cutscene/dialogue/Conversation.hx
+++ b/source/funkin/play/cutscene/dialogue/Conversation.hx
@@ -50,7 +50,7 @@ class Conversation extends FlxSpriteGroup implements IDialogueScriptedClass
    */
   var currentDialogueEntry:Int = 0;
 
-  var currentDialogueEntryCount(get, null):Int;
+  var currentDialogueEntryCount(get, never):Int;
 
   function get_currentDialogueEntryCount():Int
   {
@@ -62,14 +62,14 @@ class Conversation extends FlxSpriteGroup implements IDialogueScriptedClass
   * **/
   var currentDialogueLine:Int = 0;
 
-  var currentDialogueLineCount(get, null):Int;
+  var currentDialogueLineCount(get, never):Int;
 
   function get_currentDialogueLineCount():Int
   {
     return currentDialogueEntryData.text.length;
   }
 
-  var currentDialogueEntryData(get, null):DialogueEntryData;
+  var currentDialogueEntryData(get, never):DialogueEntryData;
 
   function get_currentDialogueEntryData():DialogueEntryData
   {
@@ -79,7 +79,7 @@ class Conversation extends FlxSpriteGroup implements IDialogueScriptedClass
     return conversationData.dialogue[currentDialogueEntry];
   }
 
-  var currentDialogueLineString(get, null):String;
+  var currentDialogueLineString(get, never):String;
 
   function get_currentDialogueLineString():String
   {
diff --git a/source/funkin/play/cutscene/dialogue/DialogueBox.hx b/source/funkin/play/cutscene/dialogue/DialogueBox.hx
index bfc0e9233..cdac3c233 100644
--- a/source/funkin/play/cutscene/dialogue/DialogueBox.hx
+++ b/source/funkin/play/cutscene/dialogue/DialogueBox.hx
@@ -13,7 +13,7 @@ import flixel.util.FlxColor;
 class DialogueBox extends FlxSpriteGroup implements IDialogueScriptedClass
 {
   public final dialogueBoxId:String;
-  public var dialogueBoxName(get, null):String;
+  public var dialogueBoxName(get, never):String;
 
   function get_dialogueBoxName():String
   {
diff --git a/source/funkin/play/cutscene/dialogue/Speaker.hx b/source/funkin/play/cutscene/dialogue/Speaker.hx
index 1fb341009..d7ed004f1 100644
--- a/source/funkin/play/cutscene/dialogue/Speaker.hx
+++ b/source/funkin/play/cutscene/dialogue/Speaker.hx
@@ -8,7 +8,7 @@ import funkin.modding.IScriptedClass.IDialogueScriptedClass;
 
 /**
  * The character sprite which displays during dialogue.
- * 
+ *
  * Most conversations have two speakers, with one being flipped.
  */
 class Speaker extends FlxSprite implements IDialogueScriptedClass
@@ -26,7 +26,7 @@ class Speaker extends FlxSprite implements IDialogueScriptedClass
   /**
    * A readable name for this speaker.
    */
-  public var speakerName(get, null):String;
+  public var speakerName(get, never):String;
 
   function get_speakerName():String
   {
@@ -129,7 +129,7 @@ class Speaker extends FlxSprite implements IDialogueScriptedClass
 
   /**
    * Set the sprite scale to the appropriate value.
-   * @param scale 
+   * @param scale
    */
   public function setScale(scale:Null<Float>):Void
   {
@@ -184,7 +184,7 @@ class Speaker extends FlxSprite implements IDialogueScriptedClass
   /**
    * Ensure that a given animation exists before playing it.
    * Will gracefully check for name, then name with stripped suffixes, then 'idle', then fail to play.
-   * @param name 
+   * @param name
    */
   function correctAnimationName(name:String):String
   {
diff --git a/source/funkin/play/notes/Strumline.hx b/source/funkin/play/notes/Strumline.hx
index 8847636bd..2b21e6b7e 100644
--- a/source/funkin/play/notes/Strumline.hx
+++ b/source/funkin/play/notes/Strumline.hx
@@ -31,7 +31,7 @@ class Strumline extends FlxSpriteGroup
   static final KEY_COUNT:Int = 4;
   static final NOTE_SPLASH_CAP:Int = 6;
 
-  static var RENDER_DISTANCE_MS(get, null):Float;
+  static var RENDER_DISTANCE_MS(get, never):Float;
 
   static function get_RENDER_DISTANCE_MS():Float
   {
diff --git a/source/funkin/play/notes/SustainTrail.hx b/source/funkin/play/notes/SustainTrail.hx
index 72d22191b..4bcbe0528 100644
--- a/source/funkin/play/notes/SustainTrail.hx
+++ b/source/funkin/play/notes/SustainTrail.hx
@@ -31,7 +31,7 @@ class SustainTrail extends FlxSprite
   public var noteDirection:NoteDirection = 0;
   public var sustainLength(default, set):Float = 0; // millis
   public var fullSustainLength:Float = 0;
-  public var noteData:SongNoteData;
+  public var noteData:Null<SongNoteData>;
 
   public var cover:NoteHoldCover = null;
 
diff --git a/source/funkin/play/song/SongValidator.hx b/source/funkin/play/song/SongValidator.hx
index 16ea88664..11cc758b9 100644
--- a/source/funkin/play/song/SongValidator.hx
+++ b/source/funkin/play/song/SongValidator.hx
@@ -20,7 +20,7 @@ class SongValidator
   public static final DEFAULT_STAGE:String = "mainStage";
   public static final DEFAULT_SCROLLSPEED:Float = 1.0;
 
-  public static var DEFAULT_GENERATEDBY(get, null):String;
+  public static var DEFAULT_GENERATEDBY(get, never):String;
 
   static function get_DEFAULT_GENERATEDBY():String
   {
diff --git a/source/funkin/ui/debug/charting/ChartEditorCommand.hx b/source/funkin/ui/debug/charting/ChartEditorCommand.hx
index fd179c481..f0ecb573b 100644
--- a/source/funkin/ui/debug/charting/ChartEditorCommand.hx
+++ b/source/funkin/ui/debug/charting/ChartEditorCommand.hx
@@ -35,6 +35,7 @@ interface ChartEditorCommand
   public function toString():String;
 }
 
+@:nullSafety
 class AddNotesCommand implements ChartEditorCommand
 {
   var notes:Array<SongNoteData>;
@@ -98,6 +99,7 @@ class AddNotesCommand implements ChartEditorCommand
   }
 }
 
+@:nullSafety
 class RemoveNotesCommand implements ChartEditorCommand
 {
   var notes:Array<SongNoteData>;
@@ -153,6 +155,7 @@ class RemoveNotesCommand implements ChartEditorCommand
 /**
  * Appends one or more items to the selection.
  */
+@:nullSafety
 class SelectItemsCommand implements ChartEditorCommand
 {
   var notes:Array<SongNoteData>;
@@ -220,6 +223,7 @@ class SelectItemsCommand implements ChartEditorCommand
   }
 }
 
+@:nullSafety
 class AddEventsCommand implements ChartEditorCommand
 {
   var events:Array<SongEventData>;
@@ -278,6 +282,7 @@ class AddEventsCommand implements ChartEditorCommand
   }
 }
 
+@:nullSafety
 class RemoveEventsCommand implements ChartEditorCommand
 {
   var events:Array<SongEventData>;
@@ -327,6 +332,7 @@ class RemoveEventsCommand implements ChartEditorCommand
   }
 }
 
+@:nullSafety
 class RemoveItemsCommand implements ChartEditorCommand
 {
   var notes:Array<SongNoteData>;
@@ -385,6 +391,7 @@ class RemoveItemsCommand implements ChartEditorCommand
   }
 }
 
+@:nullSafety
 class SwitchDifficultyCommand implements ChartEditorCommand
 {
   var prevDifficulty:String;
@@ -424,6 +431,7 @@ class SwitchDifficultyCommand implements ChartEditorCommand
   }
 }
 
+@:nullSafety
 class DeselectItemsCommand implements ChartEditorCommand
 {
   var notes:Array<SongNoteData>;
@@ -478,6 +486,7 @@ class DeselectItemsCommand implements ChartEditorCommand
  * Sets the selection rather than appends it.
  * Deselects any notes that are not in the new selection.
  */
+@:nullSafety
 class SetItemSelectionCommand implements ChartEditorCommand
 {
   var notes:Array<SongNoteData>;
@@ -518,6 +527,7 @@ class SetItemSelectionCommand implements ChartEditorCommand
   }
 }
 
+@:nullSafety
 class SelectAllItemsCommand implements ChartEditorCommand
 {
   var previousNoteSelection:Array<SongNoteData>;
@@ -553,6 +563,7 @@ class SelectAllItemsCommand implements ChartEditorCommand
   }
 }
 
+@:nullSafety
 class InvertSelectedItemsCommand implements ChartEditorCommand
 {
   var previousNoteSelection:Array<SongNoteData>;
@@ -587,6 +598,7 @@ class InvertSelectedItemsCommand implements ChartEditorCommand
   }
 }
 
+@:nullSafety
 class DeselectAllItemsCommand implements ChartEditorCommand
 {
   var previousNoteSelection:Array<SongNoteData>;
@@ -622,6 +634,7 @@ class DeselectAllItemsCommand implements ChartEditorCommand
   }
 }
 
+@:nullSafety
 class CutItemsCommand implements ChartEditorCommand
 {
   var notes:Array<SongNoteData>;
@@ -679,14 +692,16 @@ class CutItemsCommand implements ChartEditorCommand
   }
 }
 
+@:nullSafety
 class FlipNotesCommand implements ChartEditorCommand
 {
-  var notes:Array<SongNoteData>;
-  var flippedNotes:Array<SongNoteData>;
+  var notes:Array<SongNoteData> = [];
+  var flippedNotes:Array<SongNoteData> = [];
 
   public function new(notes:Array<SongNoteData>)
   {
     this.notes = notes;
+    this.flippedNotes = SongDataUtils.flipNotes(notes);
   }
 
   public function execute(state:ChartEditorState):Void
@@ -695,7 +710,6 @@ class FlipNotesCommand implements ChartEditorCommand
     state.currentSongChartNoteData = SongDataUtils.subtractNotes(state.currentSongChartNoteData, notes);
 
     // Add the flipped notes.
-    flippedNotes = SongDataUtils.flipNotes(notes);
     state.currentSongChartNoteData = state.currentSongChartNoteData.concat(flippedNotes);
 
     state.currentNoteSelection = flippedNotes;
@@ -729,12 +743,13 @@ class FlipNotesCommand implements ChartEditorCommand
   }
 }
 
+@:nullSafety
 class PasteItemsCommand implements ChartEditorCommand
 {
   var targetTimestamp:Float;
   // Notes we added with this command, for undo.
-  var addedNotes:Array<SongNoteData>;
-  var addedEvents:Array<SongEventData>;
+  var addedNotes:Array<SongNoteData> = [];
+  var addedEvents:Array<SongEventData> = [];
 
   public function new(targetTimestamp:Float)
   {
@@ -787,6 +802,7 @@ class PasteItemsCommand implements ChartEditorCommand
   }
 }
 
+@:nullSafety
 class ExtendNoteLengthCommand implements ChartEditorCommand
 {
   var note:SongNoteData;
diff --git a/source/funkin/ui/debug/charting/ChartEditorDialogHandler.hx b/source/funkin/ui/debug/charting/ChartEditorDialogHandler.hx
index a32aed862..59bee0d74 100644
--- a/source/funkin/ui/debug/charting/ChartEditorDialogHandler.hx
+++ b/source/funkin/ui/debug/charting/ChartEditorDialogHandler.hx
@@ -41,6 +41,7 @@ using Lambda;
 /**
  * Handles dialogs for the new Chart Editor.
  */
+@:nullSafety
 class ChartEditorDialogHandler
 {
   static final CHART_EDITOR_DIALOG_ABOUT_LAYOUT:String = Paths.ui('chart-editor/dialogs/about');
@@ -60,7 +61,7 @@ class ChartEditorDialogHandler
    * @param state The current chart editor state.
    * @return The dialog that was opened.
    */
-  public static inline function openAboutDialog(state:ChartEditorState):Dialog
+  public static inline function openAboutDialog(state:ChartEditorState):Null<Dialog>
   {
     return openDialog(state, CHART_EDITOR_DIALOG_ABOUT_LAYOUT, true, true);
   }
@@ -71,12 +72,14 @@ class ChartEditorDialogHandler
    * @param closable Whether the dialog can be closed by the user.
    * @return The dialog that was opened.
    */
-  public static function openWelcomeDialog(state:ChartEditorState, closable:Bool = true):Dialog
+  public static function openWelcomeDialog(state:ChartEditorState, closable:Bool = true):Null<Dialog>
   {
-    var dialog:Dialog = openDialog(state, CHART_EDITOR_DIALOG_WELCOME_LAYOUT, true, closable);
+    var dialog:Null<Dialog> = openDialog(state, CHART_EDITOR_DIALOG_WELCOME_LAYOUT, true, closable);
+    if (dialog == null) throw 'Could not locate Welcome dialog';
 
     // Add handlers to the "Create From Song" section.
-    var linkCreateBasic:Link = dialog.findComponent('splashCreateFromSongBasic', Link);
+    var linkCreateBasic:Null<Link> = dialog.findComponent('splashCreateFromSongBasic', Link);
+    if (linkCreateBasic == null) throw 'Could not locate splashCreateFromSongBasic link in Welcome dialog';
     linkCreateBasic.onClick = function(_event) {
       // Hide the welcome dialog
       dialog.hideDialog(DialogButton.CANCEL);
@@ -87,7 +90,8 @@ class ChartEditorDialogHandler
       openCreateSongWizard(state, false);
     }
 
-    var linkImportChartLegacy:Link = dialog.findComponent('splashImportChartLegacy', Link);
+    var linkImportChartLegacy:Null<Link> = dialog.findComponent('splashImportChartLegacy', Link);
+    if (linkImportChartLegacy == null) throw 'Could not locate splashImportChartLegacy link in Welcome dialog';
     linkImportChartLegacy.onClick = function(_event) {
       // Hide the welcome dialog
       dialog.hideDialog(DialogButton.CANCEL);
@@ -96,7 +100,8 @@ class ChartEditorDialogHandler
       openImportChartWizard(state, 'legacy', false);
     };
 
-    var buttonBrowse:Button = dialog.findComponent('splashBrowse', Button);
+    var buttonBrowse:Null<Button> = dialog.findComponent('splashBrowse', Button);
+    if (buttonBrowse == null) throw 'Could not locate splashBrowse button in Welcome dialog';
     buttonBrowse.onClick = function(_event) {
       // Hide the welcome dialog
       dialog.hideDialog(DialogButton.CANCEL);
@@ -105,22 +110,29 @@ class ChartEditorDialogHandler
       openBrowseWizard(state, false);
     }
 
-    var splashTemplateContainer:VBox = dialog.findComponent('splashTemplateContainer', VBox);
+    var splashTemplateContainer:Null<VBox> = dialog.findComponent('splashTemplateContainer', VBox);
+    if (splashTemplateContainer == null) throw 'Could not locate splashTemplateContainer in Welcome dialog';
 
     var songList:Array<String> = SongDataParser.listSongIds();
     songList.sort(SortUtil.alphabetically);
 
     for (targetSongId in songList)
     {
-      var songData:Song = SongDataParser.fetchSong(targetSongId);
+      var songData:Null<Song> = SongDataParser.fetchSong(targetSongId);
 
       if (songData == null) continue;
 
-      var songName:Null<String> = songData.getDifficulty('normal') ?.songName;
-      if (songName == null) songName = songData.getDifficulty() ?.songName;
+      var diffNormal:Null<SongDifficulty> = songData.getDifficulty('normal');
+      var songName:Null<String> = diffNormal?.songName;
+      if (songName == null)
+      {
+        var diffDefault:Null<SongDifficulty> = songData.getDifficulty();
+        songName = diffDefault?.songName;
+      }
       if (songName == null)
       {
         trace('[WARN] Could not fetch song name for ${targetSongId}');
+        continue;
       }
 
       var linkTemplateSong:Link = new FunkinLink();
@@ -185,7 +197,8 @@ class ChartEditorDialogHandler
   {
     // Open the "Open Chart" wizard
     // Step 1. Open Chart
-    var openChartDialog:Dialog = openImportChartDialog(state, format);
+    var openChartDialog:Null<Dialog> = openImportChartDialog(state, format);
+    if (openChartDialog == null) throw 'Could not locate Import Chart dialog';
     openChartDialog.onDialogClosed = function(_event) {
       state.isHaxeUIDialogOpen = false;
       if (_event.button == DialogButton.APPLY)
@@ -261,15 +274,18 @@ class ChartEditorDialogHandler
   @:haxe.warning("-WVarInit") // Hide the warning about the onDropFile handler.
   public static function openUploadInstDialog(state:ChartEditorState, closable:Bool = true):Dialog
   {
-    var dialog:Dialog = openDialog(state, CHART_EDITOR_DIALOG_UPLOAD_INST_LAYOUT, true, closable);
+    var dialog:Null<Dialog> = openDialog(state, CHART_EDITOR_DIALOG_UPLOAD_INST_LAYOUT, true, closable);
+    if (dialog == null) throw 'Could not locate Upload Instrumental dialog';
 
-    var buttonCancel:Button = dialog.findComponent('dialogCancel', Button);
+    var buttonCancel:Null<Button> = dialog.findComponent('dialogCancel', Button);
+    if (buttonCancel == null) throw 'Could not locate dialogCancel button in Upload Instrumental dialog';
 
     buttonCancel.onClick = function(_event) {
       dialog.hideDialog(DialogButton.CANCEL);
     }
 
-    var instrumentalBox:Box = dialog.findComponent('instrumentalBox', Box);
+    var instrumentalBox:Null<Box> = dialog.findComponent('instrumentalBox', Box);
+    if (instrumentalBox == null) throw 'Could not locate instrumentalBox in Upload Instrumental dialog';
 
     instrumentalBox.onMouseOver = function(_event) {
       instrumentalBox.swapClass('upload-bg', 'upload-bg-hover');
@@ -286,7 +302,7 @@ class ChartEditorDialogHandler
     instrumentalBox.onClick = function(_event) {
       Dialogs.openBinaryFile('Open Instrumental', [
         {label: 'Audio File (.ogg)', extension: 'ogg'}], function(selectedFile:SelectedFileInfo) {
-          if (selectedFile != null)
+          if (selectedFile != null && selectedFile.bytes != null)
           {
             if (state.loadInstrumentalFromBytes(selectedFile.bytes))
             {
@@ -343,7 +359,7 @@ class ChartEditorDialogHandler
       }
       else
       {
-        var message:String = if (!ChartEditorState.SUPPORTED_MUSIC_FORMATS.contains(path.ext))
+        var message:String = if (!ChartEditorState.SUPPORTED_MUSIC_FORMATS.contains(path.ext ?? ''))
         {
           'File format (${path.ext}) not supported for instrumental track (${path.file}.${path.ext})';
         }
@@ -438,15 +454,17 @@ class ChartEditorDialogHandler
   @:haxe.warning("-WVarInit")
   public static function openSongMetadataDialog(state:ChartEditorState):Dialog
   {
-    var dialog:Dialog = openDialog(state, CHART_EDITOR_DIALOG_SONG_METADATA_LAYOUT, true, false);
-
-    var buttonCancel:Button = dialog.findComponent('dialogCancel', Button);
+    var dialog:Null<Dialog> = openDialog(state, CHART_EDITOR_DIALOG_SONG_METADATA_LAYOUT, true, false);
+    if (dialog == null) throw 'Could not locate Song Metadata dialog';
 
+    var buttonCancel:Null<Button> = dialog.findComponent('dialogCancel', Button);
+    if (buttonCancel == null) throw 'Could not locate dialogCancel button in Song Metadata dialog';
     buttonCancel.onClick = function(_event) {
       dialog.hideDialog(DialogButton.CANCEL);
     }
 
-    var dialogSongName:TextField = dialog.findComponent('dialogSongName', TextField);
+    var dialogSongName:Null<TextField> = dialog.findComponent('dialogSongName', TextField);
+    if (dialogSongName == null) throw 'Could not locate dialogSongName TextField in Song Metadata dialog';
     dialogSongName.onChange = function(event:UIEvent) {
       var valid:Bool = event.target.text != null && event.target.text != '';
 
@@ -457,12 +475,13 @@ class ChartEditorDialogHandler
       }
       else
       {
-        state.currentSongMetadata.songName = null;
+        state.currentSongMetadata.songName = "";
       }
     };
-    state.currentSongMetadata.songName = null;
+    state.currentSongMetadata.songName = "";
 
-    var dialogSongArtist:TextField = dialog.findComponent('dialogSongArtist', TextField);
+    var dialogSongArtist:Null<TextField> = dialog.findComponent('dialogSongArtist', TextField);
+    if (dialogSongArtist == null) throw 'Could not locate dialogSongArtist TextField in Song Metadata dialog';
     dialogSongArtist.onChange = function(event:UIEvent) {
       var valid:Bool = event.target.text != null && event.target.text != '';
 
@@ -473,26 +492,29 @@ class ChartEditorDialogHandler
       }
       else
       {
-        state.currentSongMetadata.artist = null;
+        state.currentSongMetadata.artist = "";
       }
     };
-    state.currentSongMetadata.artist = null;
+    state.currentSongMetadata.artist = "";
 
-    var dialogStage:DropDown = dialog.findComponent('dialogStage', DropDown);
+    var dialogStage:Null<DropDown> = dialog.findComponent('dialogStage', DropDown);
+    if (dialogStage == null) throw 'Could not locate dialogStage DropDown in Song Metadata dialog';
     dialogStage.onChange = function(event:UIEvent) {
       if (event.data == null && event.data.id == null) return;
       state.currentSongMetadata.playData.stage = event.data.id;
     };
-    state.currentSongMetadata.playData.stage = null;
+    state.currentSongMetadata.playData.stage = 'mainStage';
 
-    var dialogNoteSkin:DropDown = dialog.findComponent('dialogNoteSkin', DropDown);
+    var dialogNoteSkin:Null<DropDown> = dialog.findComponent('dialogNoteSkin', DropDown);
+    if (dialogNoteSkin == null) throw 'Could not locate dialogNoteSkin DropDown in Song Metadata dialog';
     dialogNoteSkin.onChange = function(event:UIEvent) {
       if (event.data.id == null) return;
       state.currentSongMetadata.playData.noteSkin = event.data.id;
     };
-    state.currentSongMetadata.playData.noteSkin = null;
+    state.currentSongMetadata.playData.noteSkin = 'funkin';
 
-    var dialogBPM:NumberStepper = dialog.findComponent('dialogBPM', NumberStepper);
+    var dialogBPM:Null<NumberStepper> = dialog.findComponent('dialogBPM', NumberStepper);
+    if (dialogBPM == null) throw 'Could not locate dialogBPM NumberStepper in Song Metadata dialog';
     dialogBPM.onChange = function(event:UIEvent) {
       if (event.value == null || event.value <= 0) return;
 
@@ -511,8 +533,10 @@ class ChartEditorDialogHandler
       state.currentSongMetadata.timeChanges = timeChanges;
     };
 
-    var dialogCharGrid:PropertyGrid = dialog.findComponent('dialogCharGrid', PropertyGrid);
-    var dialogCharAdd:Button = dialog.findComponent('dialogCharAdd', Button);
+    var dialogCharGrid:Null<PropertyGrid> = dialog.findComponent('dialogCharGrid', PropertyGrid);
+    if (dialogCharGrid == null) throw 'Could not locate dialogCharGrid PropertyGrid in Song Metadata dialog';
+    var dialogCharAdd:Null<Button> = dialog.findComponent('dialogCharAdd', Button);
+    if (dialogCharAdd == null) throw 'Could not locate dialogCharAdd Button in Song Metadata dialog';
     dialogCharAdd.onClick = function(event:UIEvent) {
       var charGroup:PropertyGroup;
       charGroup = buildCharGroup(state, null, () -> dialogCharGrid.removeComponent(charGroup));
@@ -522,15 +546,16 @@ class ChartEditorDialogHandler
     // Empty the character list.
     state.currentSongMetadata.playData.playableChars = {};
     // Add at least one character group with no Remove button.
-    dialogCharGrid.addComponent(buildCharGroup(state, 'bf', null));
+    dialogCharGrid.addComponent(buildCharGroup(state, 'bf'));
 
-    var dialogContinue:Button = dialog.findComponent('dialogContinue', Button);
+    var dialogContinue:Null<Button> = dialog.findComponent('dialogContinue', Button);
+    if (dialogContinue == null) throw 'Could not locate dialogContinue button in Song Metadata dialog';
     dialogContinue.onClick = (_event) -> dialog.hideDialog(DialogButton.APPLY);
 
     return dialog;
   }
 
-  static function buildCharGroup(state:ChartEditorState, key:String = null, removeFunc:Void->Void):PropertyGroup
+  static function buildCharGroup(state:ChartEditorState, key:String = '', removeFunc:Void->Void = null):PropertyGroup
   {
     var groupKey:String = key;
 
@@ -555,32 +580,36 @@ class ChartEditorDialogHandler
 
     var removeGroup:Void->Void = function() {
       state.currentSongMetadata.playData.playableChars.remove(groupKey);
-      removeFunc();
+      if (removeFunc != null) removeFunc();
     }
 
     var charData:SongPlayableChar = getCharData();
 
     var charGroup:PropertyGroup = cast state.buildComponent(CHART_EDITOR_DIALOG_SONG_METADATA_CHARGROUP_LAYOUT);
 
-    var charGroupPlayer:DropDown = charGroup.findComponent('charGroupPlayer', DropDown);
+    var charGroupPlayer:Null<DropDown> = charGroup.findComponent('charGroupPlayer', DropDown);
+    if (charGroupPlayer == null) throw 'Could not locate charGroupPlayer DropDown in Song Metadata dialog';
     charGroupPlayer.onChange = function(event:UIEvent) {
       charGroup.text = event.data.text;
       moveCharGroup(event.data.id);
     };
 
-    var charGroupOpponent:DropDown = charGroup.findComponent('charGroupOpponent', DropDown);
+    var charGroupOpponent:Null<DropDown> = charGroup.findComponent('charGroupOpponent', DropDown);
+    if (charGroupOpponent == null) throw 'Could not locate charGroupOpponent DropDown in Song Metadata dialog';
     charGroupOpponent.onChange = function(event:UIEvent) {
       charData.opponent = event.data.id;
     };
     charGroupOpponent.value = getCharData().opponent;
 
-    var charGroupGirlfriend:DropDown = charGroup.findComponent('charGroupGirlfriend', DropDown);
+    var charGroupGirlfriend:Null<DropDown> = charGroup.findComponent('charGroupGirlfriend', DropDown);
+    if (charGroupGirlfriend == null) throw 'Could not locate charGroupGirlfriend DropDown in Song Metadata dialog';
     charGroupGirlfriend.onChange = function(event:UIEvent) {
       charData.girlfriend = event.data.id;
     };
     charGroupGirlfriend.value = getCharData().girlfriend;
 
-    var charGroupRemove:Button = charGroup.findComponent('charGroupRemove', Button);
+    var charGroupRemove:Null<Button> = charGroup.findComponent('charGroupRemove', Button);
+    if (charGroupRemove == null) throw 'Could not locate charGroupRemove Button in Song Metadata dialog';
     charGroupRemove.onClick = function(event:UIEvent) {
       removeGroup();
     };
@@ -602,21 +631,26 @@ class ChartEditorDialogHandler
 
     for (charKey in state.currentSongMetadata.playData.playableChars.keys())
     {
-      var charData:SongPlayableChar = state.currentSongMetadata.playData.playableChars.get(charKey);
+      var charData:Null<SongPlayableChar> = state.currentSongMetadata.playData.playableChars.get(charKey);
+      if (charData == null) continue;
       charIdsForVocals.push(charKey);
       if (charData.opponent != null) charIdsForVocals.push(charData.opponent);
     }
 
-    var dialog:Dialog = openDialog(state, CHART_EDITOR_DIALOG_UPLOAD_VOCALS_LAYOUT, true, closable);
+    var dialog:Null<Dialog> = openDialog(state, CHART_EDITOR_DIALOG_UPLOAD_VOCALS_LAYOUT, true, closable);
+    if (dialog == null) throw 'Could not locate Upload Vocals dialog';
 
-    var dialogContainer:Component = dialog.findComponent('vocalContainer');
+    var dialogContainer:Null<Component> = dialog.findComponent('vocalContainer');
+    if (dialogContainer == null) throw 'Could not locate vocalContainer in Upload Vocals dialog';
 
-    var buttonCancel:Button = dialog.findComponent('dialogCancel', Button);
+    var buttonCancel:Null<Button> = dialog.findComponent('dialogCancel', Button);
+    if (buttonCancel == null) throw 'Could not locate dialogCancel button in Upload Vocals dialog';
     buttonCancel.onClick = function(_event) {
       dialog.hideDialog(DialogButton.CANCEL);
     }
 
-    var dialogNoVocals:Button = dialog.findComponent('dialogNoVocals', Button);
+    var dialogNoVocals:Null<Button> = dialog.findComponent('dialogNoVocals', Button);
+    if (dialogNoVocals == null) throw 'Could not locate dialogNoVocals button in Upload Vocals dialog';
     dialogNoVocals.onClick = function(_event) {
       // Dismiss
       dialog.hideDialog(DialogButton.APPLY);
@@ -625,12 +659,13 @@ class ChartEditorDialogHandler
     for (charKey in charIdsForVocals)
     {
       trace('Adding vocal upload for character ${charKey}');
-      var charMetadata:CharacterData = CharacterDataParser.fetchCharacterData(charKey);
+      var charMetadata:Null<CharacterData> = CharacterDataParser.fetchCharacterData(charKey);
       var charName:String = charMetadata != null ? charMetadata.name : charKey;
 
       var vocalsEntry:Component = state.buildComponent(CHART_EDITOR_DIALOG_UPLOAD_VOCALS_ENTRY_LAYOUT);
 
-      var vocalsEntryLabel:Label = vocalsEntry.findComponent('vocalsEntryLabel', Label);
+      var vocalsEntryLabel:Null<Label> = vocalsEntry.findComponent('vocalsEntryLabel', Label);
+      if (vocalsEntryLabel == null) throw 'Could not locate vocalsEntryLabel in Upload Vocals dialog';
       #if FILE_DROP_SUPPORTED
       vocalsEntryLabel.text = 'Drag and drop vocals for $charName here, or click to browse.';
       #else
@@ -663,7 +698,7 @@ class ChartEditorDialogHandler
         }
         else
         {
-          var message:String = if (!ChartEditorState.SUPPORTED_MUSIC_FORMATS.contains(path.ext))
+          var message:String = if (!ChartEditorState.SUPPORTED_MUSIC_FORMATS.contains(path.ext ?? ''))
           {
             'File format (${path.ext}) not supported for vocal track (${path.file}.${path.ext})';
           }
@@ -694,7 +729,7 @@ class ChartEditorDialogHandler
       vocalsEntry.onClick = function(_event) {
         Dialogs.openBinaryFile('Open $charName Vocals', [
           {label: 'Audio File (.ogg)', extension: 'ogg'}], function(selectedFile) {
-            if (selectedFile != null)
+            if (selectedFile != null && selectedFile.bytes != null)
             {
               trace('Selected file: ' + selectedFile.name);
               #if FILE_DROP_SUPPORTED
@@ -716,7 +751,8 @@ class ChartEditorDialogHandler
       dialogContainer.addComponent(vocalsEntry);
     }
 
-    var dialogContinue:Button = dialog.findComponent('dialogContinue', Button);
+    var dialogContinue:Null<Button> = dialog.findComponent('dialogContinue', Button);
+    if (dialogContinue == null) throw 'Could not locate dialogContinue button in Upload Vocals dialog';
     dialogContinue.onClick = function(_event) {
       // Dismiss
       dialog.hideDialog(DialogButton.APPLY);
@@ -734,20 +770,25 @@ class ChartEditorDialogHandler
   @:haxe.warning('-WVarInit')
   public static function openChartDialog(state:ChartEditorState, closable:Bool = true):Dialog
   {
-    var dialog:Dialog = openDialog(state, CHART_EDITOR_DIALOG_OPEN_CHART_LAYOUT, true, closable);
+    var dialog:Null<Dialog> = openDialog(state, CHART_EDITOR_DIALOG_OPEN_CHART_LAYOUT, true, closable);
+    if (dialog == null) throw 'Could not locate Open Chart dialog';
 
-    var buttonCancel:Button = dialog.findComponent('dialogCancel', Button);
+    var buttonCancel:Null<Button> = dialog.findComponent('dialogCancel', Button);
+    if (buttonCancel == null) throw 'Could not locate dialogCancel button in Open Chart dialog';
     buttonCancel.onClick = function(_event) {
       dialog.hideDialog(DialogButton.CANCEL);
     }
 
-    var chartContainerA:Component = dialog.findComponent('chartContainerA');
-    var chartContainerB:Component = dialog.findComponent('chartContainerB');
+    var chartContainerA:Null<Component> = dialog.findComponent('chartContainerA');
+    if (chartContainerA == null) throw 'Could not locate chartContainerA in Open Chart dialog';
+    var chartContainerB:Null<Component> = dialog.findComponent('chartContainerB');
+    if (chartContainerB == null) throw 'Could not locate chartContainerB in Open Chart dialog';
 
     var songMetadata:Map<String, SongMetadata> = [];
     var songChartData:Map<String, SongChartData> = [];
 
-    var buttonContinue:Button = dialog.findComponent('dialogContinue', Button);
+    var buttonContinue:Null<Button> = dialog.findComponent('dialogContinue', Button);
+    if (buttonContinue == null) throw 'Could not locate dialogContinue button in Open Chart dialog';
     buttonContinue.onClick = function(_event) {
       state.loadSong(songMetadata, songChartData);
 
@@ -768,7 +809,8 @@ class ChartEditorDialogHandler
 
       // Build an entry for -chart.json.
       var songDefaultChartDataEntry:Component = state.buildComponent(CHART_EDITOR_DIALOG_OPEN_CHART_ENTRY_LAYOUT);
-      var songDefaultChartDataEntryLabel:Label = songDefaultChartDataEntry.findComponent('chartEntryLabel', Label);
+      var songDefaultChartDataEntryLabel:Null<Label> = songDefaultChartDataEntry.findComponent('chartEntryLabel', Label);
+      if (songDefaultChartDataEntryLabel == null) throw 'Could not locate chartEntryLabel in Open Chart dialog';
       #if FILE_DROP_SUPPORTED
       songDefaultChartDataEntryLabel.text = 'Drag and drop <song>-chart.json file, or click to browse.';
       #else
@@ -783,7 +825,8 @@ class ChartEditorDialogHandler
       {
         // Build entries for -metadata-<variation>.json.
         var songVariationMetadataEntry:Component = state.buildComponent(CHART_EDITOR_DIALOG_OPEN_CHART_ENTRY_LAYOUT);
-        var songVariationMetadataEntryLabel:Label = songVariationMetadataEntry.findComponent('chartEntryLabel', Label);
+        var songVariationMetadataEntryLabel:Null<Label> = songVariationMetadataEntry.findComponent('chartEntryLabel', Label);
+        if (songVariationMetadataEntryLabel == null) throw 'Could not locate chartEntryLabel in Open Chart dialog';
         #if FILE_DROP_SUPPORTED
         songVariationMetadataEntryLabel.text = 'Drag and drop <song>-metadata-${variation}.json file, or click to browse.';
         #else
@@ -806,7 +849,8 @@ class ChartEditorDialogHandler
 
         // Build entries for -chart-<variation>.json.
         var songVariationChartDataEntry:Component = state.buildComponent(CHART_EDITOR_DIALOG_OPEN_CHART_ENTRY_LAYOUT);
-        var songVariationChartDataEntryLabel:Label = songVariationChartDataEntry.findComponent('chartEntryLabel', Label);
+        var songVariationChartDataEntryLabel:Null<Label> = songVariationChartDataEntry.findComponent('chartEntryLabel', Label);
+        if (songVariationChartDataEntryLabel == null) throw 'Could not locate chartEntryLabel in Open Chart dialog';
         #if FILE_DROP_SUPPORTED
         songVariationChartDataEntryLabel.text = 'Drag and drop <song>-chart-${variation}.json file, or click to browse.';
         #else
@@ -877,7 +921,7 @@ class ChartEditorDialogHandler
     onClickMetadataVariation = function(variation:String, label:Label, _event:UIEvent) {
       Dialogs.openBinaryFile('Open Chart ($variation) Metadata', [
         {label: 'JSON File (.json)', extension: 'json'}], function(selectedFile) {
-          if (selectedFile != null)
+          if (selectedFile != null && selectedFile.bytes != null)
           {
             trace('Selected file: ' + selectedFile.name);
 
@@ -944,7 +988,7 @@ class ChartEditorDialogHandler
     onClickChartDataVariation = function(variation:String, label:Label, _event:UIEvent) {
       Dialogs.openBinaryFile('Open Chart ($variation) Metadata', [
         {label: 'JSON File (.json)', extension: 'json'}], function(selectedFile) {
-          if (selectedFile != null)
+          if (selectedFile != null && selectedFile.bytes != null)
           {
             trace('Selected file: ' + selectedFile.name);
 
@@ -978,12 +1022,8 @@ class ChartEditorDialogHandler
     }
 
     var metadataEntry:Component = state.buildComponent(CHART_EDITOR_DIALOG_OPEN_CHART_ENTRY_LAYOUT);
-    var metadataEntryLabel:Label = metadataEntry.findComponent('chartEntryLabel', Label);
-    #if FILE_DROP_UNSUPPORTED
-    trace('File drop unsupported');
-    #elseif FILE_DROP_SUPPORTED
-    trace('File drop supported');
-    #end
+    var metadataEntryLabel:Null<Label> = metadataEntry.findComponent('chartEntryLabel', Label);
+    if (metadataEntryLabel == null) throw 'Could not locate chartEntryLabel in Open Chart dialog';
 
     #if FILE_DROP_SUPPORTED
     metadataEntryLabel.text = 'Drag and drop <song>-metadata.json file, or click to browse.';
@@ -1014,9 +1054,10 @@ class ChartEditorDialogHandler
    * @param closable
    * @return Dialog
    */
-  public static function openImportChartDialog(state:ChartEditorState, format:String, closable:Bool = true):Dialog
+  public static function openImportChartDialog(state:ChartEditorState, format:String, closable:Bool = true):Null<Dialog>
   {
-    var dialog:Dialog = openDialog(state, CHART_EDITOR_DIALOG_IMPORT_CHART_LAYOUT, true, closable);
+    var dialog:Null<Dialog> = openDialog(state, CHART_EDITOR_DIALOG_IMPORT_CHART_LAYOUT, true, closable);
+    if (dialog == null) return null;
 
     var prettyFormat:String = switch (format)
     {
@@ -1032,13 +1073,15 @@ class ChartEditorDialogHandler
 
     dialog.title = 'Import Chart - ${prettyFormat}';
 
-    var buttonCancel:Button = dialog.findComponent('dialogCancel', Button);
+    var buttonCancel:Null<Button> = dialog.findComponent('dialogCancel', Button);
+    if (buttonCancel == null) throw 'Could not locate dialogCancel button in Import Chart dialog';
 
     buttonCancel.onClick = function(_event) {
       dialog.hideDialog(DialogButton.CANCEL);
     }
 
-    var importBox:Box = dialog.findComponent('importBox', Box);
+    var importBox:Null<Box> = dialog.findComponent('importBox', Box);
+    if (importBox == null) throw 'Could not locate importBox in Import Chart dialog';
 
     importBox.onMouseOver = function(_event) {
       importBox.swapClass('upload-bg', 'upload-bg-hover');
@@ -1052,8 +1095,8 @@ class ChartEditorDialogHandler
     var onDropFile:String->Void;
 
     importBox.onClick = function(_event) {
-      Dialogs.openBinaryFile('Import Chart - ${prettyFormat}', [fileFilter], function(selectedFile:SelectedFileInfo) {
-        if (selectedFile != null)
+      Dialogs.openBinaryFile('Import Chart - ${prettyFormat}', fileFilter != null ? [fileFilter] : [], function(selectedFile:SelectedFileInfo) {
+        if (selectedFile != null && selectedFile.bytes != null)
         {
           trace('Selected file: ' + selectedFile.fullPath);
           var selectedFileJson:Dynamic = SerializerUtil.fromJSONBytes(selectedFile.bytes);
@@ -1107,7 +1150,7 @@ class ChartEditorDialogHandler
    * @param state The current chart editor state.
    * @return The dialog that was opened.
    */
-  public static inline function openUserGuideDialog(state:ChartEditorState):Dialog
+  public static inline function openUserGuideDialog(state:ChartEditorState):Null<Dialog>
   {
     return openDialog(state, CHART_EDITOR_DIALOG_USER_GUIDE_LAYOUT, true, true);
   }
@@ -1117,9 +1160,9 @@ class ChartEditorDialogHandler
    * @param modal Makes the background uninteractable while the dialog is open.
    * @param closable Hides the close button on the dialog, preventing it from being closed unless the user interacts with the dialog.
    */
-  static function openDialog(state:ChartEditorState, key:String, modal:Bool = true, closable:Bool = true):Dialog
+  static function openDialog(state:ChartEditorState, key:String, modal:Bool = true, closable:Bool = true):Null<Dialog>
   {
-    var dialog:Dialog = cast state.buildComponent(key);
+    var dialog:Null<Dialog> = cast state.buildComponent(key);
     if (dialog == null) return null;
 
     dialog.destroyOnClose = true;
diff --git a/source/funkin/ui/debug/charting/ChartEditorEventSprite.hx b/source/funkin/ui/debug/charting/ChartEditorEventSprite.hx
index 2524f014c..4ee6eda9f 100644
--- a/source/funkin/ui/debug/charting/ChartEditorEventSprite.hx
+++ b/source/funkin/ui/debug/charting/ChartEditorEventSprite.hx
@@ -16,6 +16,7 @@ import funkin.play.song.SongData.SongEventData;
  * A event sprite that can be used to display a song event in a chart.
  * Designed to be used and reused efficiently. Has no gameplay functionality.
  */
+@:nullSafety
 class ChartEditorEventSprite extends FlxSprite
 {
   public static final DEFAULT_EVENT = 'Default';
@@ -45,16 +46,18 @@ class ChartEditorEventSprite extends FlxSprite
     refresh();
   }
 
+  static var eventFrames:Null<FlxFramesCollection> = null;
+
   /**
    * Build a set of animations to allow displaying different types of chart events.
    * @param force `true` to force rebuilding the frames.
    */
   static function buildFrames(force:Bool = false):FlxFramesCollection
   {
-    static var eventFrames:FlxFramesCollection = null;
-
     if (eventFrames != null && !force) return eventFrames;
-    eventFrames = new FlxAtlasFrames(null);
+
+    initEmptyEventFrames();
+    if (eventFrames == null) throw 'Failed to initialize empty event frames.';
 
     // Push the default event as a frame.
     var defaultFrames:FlxAtlasFrames = Paths.getSparrowAtlas('ui/chart-editor/events/$DEFAULT_EVENT');
@@ -83,6 +86,12 @@ class ChartEditorEventSprite extends FlxSprite
     return eventFrames;
   }
 
+  @:nullSafety(Off)
+  static function initEmptyEventFrames():Void
+  {
+    eventFrames = new FlxAtlasFrames(null);
+  }
+
   function buildAnimations():Void
   {
     var eventNames:Array<String> = [DEFAULT_EVENT].concat(SongEventParser.listEventIds());
@@ -133,6 +142,8 @@ class ChartEditorEventSprite extends FlxSprite
 
   public function updateEventPosition(?origin:FlxObject)
   {
+    if (this.eventData == null) return;
+
     this.x = (ChartEditorState.STRUMLINE_SIZE * 2 + 1 - 1) * ChartEditorState.GRID_SIZE;
     if (this.eventData.stepTime >= 0) this.y = this.eventData.stepTime * ChartEditorState.GRID_SIZE;
 
diff --git a/source/funkin/ui/debug/charting/ChartEditorHoldNoteSprite.hx b/source/funkin/ui/debug/charting/ChartEditorHoldNoteSprite.hx
index 5805874f6..ea021c4bb 100644
--- a/source/funkin/ui/debug/charting/ChartEditorHoldNoteSprite.hx
+++ b/source/funkin/ui/debug/charting/ChartEditorHoldNoteSprite.hx
@@ -14,6 +14,7 @@ import funkin.play.song.SongData.SongNoteData;
  * A hold note sprite that can be used to display a note in a chart.
  * Designed to be used and reused efficiently. Has no gameplay functionality.
  */
+@:nullSafety
 class ChartEditorHoldNoteSprite extends SustainTrail
 {
   /**
@@ -110,8 +111,10 @@ class ChartEditorHoldNoteSprite extends SustainTrail
     return !aboveViewArea && !belowViewArea;
   }
 
-  public function updateHoldNotePosition(?origin:FlxObject)
+  public function updateHoldNotePosition(?origin:FlxObject):Void
   {
+    if (this.noteData == null) return;
+
     var cursorColumn:Int = this.noteData.data;
 
     if (cursorColumn < 0) cursorColumn = 0;
diff --git a/source/funkin/ui/debug/charting/ChartEditorNotePreview.hx b/source/funkin/ui/debug/charting/ChartEditorNotePreview.hx
index 69655bfe5..be45676f2 100644
--- a/source/funkin/ui/debug/charting/ChartEditorNotePreview.hx
+++ b/source/funkin/ui/debug/charting/ChartEditorNotePreview.hx
@@ -10,6 +10,7 @@ import flixel.util.FlxSpriteUtil;
 /**
  * Handles the note scrollbar preview in the chart editor.
  */
+@:nullSafety
 class ChartEditorNotePreview extends FlxSprite
 {
   //
diff --git a/source/funkin/ui/debug/charting/ChartEditorNoteSprite.hx b/source/funkin/ui/debug/charting/ChartEditorNoteSprite.hx
index ca480291a..10e0f9045 100644
--- a/source/funkin/ui/debug/charting/ChartEditorNoteSprite.hx
+++ b/source/funkin/ui/debug/charting/ChartEditorNoteSprite.hx
@@ -3,6 +3,8 @@ package funkin.ui.debug.charting;
 import flixel.FlxObject;
 import flixel.FlxSprite;
 import flixel.graphics.frames.FlxFramesCollection;
+import flixel.graphics.frames.FlxAtlasFrames;
+import flixel.graphics.frames.FlxFrame;
 import flixel.graphics.frames.FlxTileFrames;
 import flixel.math.FlxPoint;
 import funkin.play.song.SongData.SongNoteData;
@@ -11,6 +13,7 @@ import funkin.play.song.SongData.SongNoteData;
  * A note sprite that can be used to display a note in a chart.
  * Designed to be used and reused efficiently. Has no gameplay functionality.
  */
+@:nullSafety
 class ChartEditorNoteSprite extends FlxSprite
 {
   /**
@@ -32,7 +35,7 @@ class ChartEditorNoteSprite extends FlxSprite
   /**
    * The name of the note style currently in use.
    */
-  public var noteStyle(get, null):String;
+  public var noteStyle(get, never):String;
 
   public function new(parent:ChartEditorState)
   {
@@ -45,6 +48,8 @@ class ChartEditorNoteSprite extends FlxSprite
       initFrameCollection();
     }
 
+    if (noteFrameCollection == null) throw 'ERROR: Could not initialize note sprite animations.';
+
     this.frames = noteFrameCollection;
 
     // Initialize all the animations, not just the one we're going to use immediately,
@@ -77,18 +82,19 @@ class ChartEditorNoteSprite extends FlxSprite
    */
   static function initFrameCollection():Void
   {
-    noteFrameCollection = new FlxFramesCollection(null, ATLAS, null);
+    buildEmptyFrameCollection();
+    if (noteFrameCollection == null) return;
 
     // TODO: Automatically iterate over the list of note skins.
 
     // Normal notes
-    var frameCollectionNormal = Paths.getSparrowAtlas('NOTE_assets');
+    var frameCollectionNormal:FlxAtlasFrames = Paths.getSparrowAtlas('NOTE_assets');
 
     for (frame in frameCollectionNormal.frames)
     {
       noteFrameCollection.pushFrame(frame);
     }
-    var frameCollectionNormal2 = Paths.getSparrowAtlas('NoteHoldNormal');
+    var frameCollectionNormal2:FlxAtlasFrames = Paths.getSparrowAtlas('NoteHoldNormal');
 
     for (frame in frameCollectionNormal2.frames)
     {
@@ -101,13 +107,20 @@ class ChartEditorNoteSprite extends FlxSprite
     var frameCollectionPixel = FlxTileFrames.fromGraphic(graphicPixel, new FlxPoint(17, 17));
     for (i in 0...frameCollectionPixel.frames.length)
     {
-      var frame = frameCollectionPixel.frames[i];
+      var frame:Null<FlxFrame> = frameCollectionPixel.frames[i];
+      if (frame == null) continue;
 
       frame.name = 'pixel' + i;
       noteFrameCollection.pushFrame(frame);
     }
   }
 
+  @:nullSafety(Off)
+  static function buildEmptyFrameCollection():Void
+  {
+    noteFrameCollection = new FlxFramesCollection(null, ATLAS, null);
+  }
+
   function set_noteData(value:Null<SongNoteData>):Null<SongNoteData>
   {
     this.noteData = value;
@@ -178,6 +191,8 @@ class ChartEditorNoteSprite extends FlxSprite
 
   public function playNoteAnimation():Void
   {
+    if (this.noteData == null) return;
+
     // Decide whether to display a note or a sustain.
     var baseAnimationName:String = 'tap';
 
diff --git a/source/funkin/ui/debug/charting/ChartEditorState.hx b/source/funkin/ui/debug/charting/ChartEditorState.hx
index 3bf684935..479a9ee2f 100644
--- a/source/funkin/ui/debug/charting/ChartEditorState.hx
+++ b/source/funkin/ui/debug/charting/ChartEditorState.hx
@@ -2702,7 +2702,7 @@ class ChartEditorState extends HaxeUIState
       var displayedHoldNoteData:Array<SongNoteData> = [];
       for (holdNoteSprite in renderedHoldNotes.members)
       {
-        if (holdNoteSprite == null || !holdNoteSprite.exists || !holdNoteSprite.visible) continue;
+        if (holdNoteSprite == null || holdNoteSprite.noteData == null || !holdNoteSprite.exists || !holdNoteSprite.visible) continue;
 
         if (!holdNoteSprite.isHoldNoteVisible(FlxG.height - MENU_BAR_HEIGHT, GRID_TOP_PAD))
         {
@@ -3198,7 +3198,8 @@ class ChartEditorState extends HaxeUIState
       difficultySelectDirty = false;
 
       // Manage the Select Difficulty tree view.
-      var difficultyToolbox:CollapsibleDialog = ChartEditorToolboxHandler.getToolbox(this, CHART_EDITOR_TOOLBOX_DIFFICULTY_LAYOUT);
+      var difficultyToolbox:Null<CollapsibleDialog> = ChartEditorToolboxHandler.getToolbox(this, CHART_EDITOR_TOOLBOX_DIFFICULTY_LAYOUT);
+      if (difficultyToolbox == null) return;
 
       var treeView:Null<TreeView> = difficultyToolbox.findComponent('difficultyToolboxTree');
       if (treeView == null) return;
@@ -3244,7 +3245,7 @@ class ChartEditorState extends HaxeUIState
     if (treeView == null)
     {
       // Manage the Select Difficulty tree view.
-      var difficultyToolbox:CollapsibleDialog = ChartEditorToolboxHandler.getToolbox(this, CHART_EDITOR_TOOLBOX_DIFFICULTY_LAYOUT);
+      var difficultyToolbox:Null<CollapsibleDialog> = ChartEditorToolboxHandler.getToolbox(this, CHART_EDITOR_TOOLBOX_DIFFICULTY_LAYOUT);
       if (difficultyToolbox == null) return;
 
       treeView = difficultyToolbox.findComponent('difficultyToolboxTree');
@@ -3258,7 +3259,7 @@ class ChartEditorState extends HaxeUIState
   function handlePlayerPreviewToolbox():Void
   {
     // Manage the Select Difficulty tree view.
-    var charPreviewToolbox:CollapsibleDialog = ChartEditorToolboxHandler.getToolbox(this, CHART_EDITOR_TOOLBOX_PLAYER_PREVIEW_LAYOUT);
+    var charPreviewToolbox:Null<CollapsibleDialog> = ChartEditorToolboxHandler.getToolbox(this, CHART_EDITOR_TOOLBOX_PLAYER_PREVIEW_LAYOUT);
     if (charPreviewToolbox == null) return;
 
     var charPlayer:Null<CharacterPlayer> = charPreviewToolbox.findComponent('charPlayer');
@@ -3293,7 +3294,7 @@ class ChartEditorState extends HaxeUIState
   function handleOpponentPreviewToolbox():Void
   {
     // Manage the Select Difficulty tree view.
-    var charPreviewToolbox:CollapsibleDialog = ChartEditorToolboxHandler.getToolbox(this, CHART_EDITOR_TOOLBOX_OPPONENT_PREVIEW_LAYOUT);
+    var charPreviewToolbox:Null<CollapsibleDialog> = ChartEditorToolboxHandler.getToolbox(this, CHART_EDITOR_TOOLBOX_OPPONENT_PREVIEW_LAYOUT);
     if (charPreviewToolbox == null) return;
 
     var charPlayer:Null<CharacterPlayer> = charPreviewToolbox.findComponent('charPlayer');
@@ -3365,7 +3366,7 @@ class ChartEditorState extends HaxeUIState
   {
     if (treeView == null)
     {
-      var difficultyToolbox:CollapsibleDialog = ChartEditorToolboxHandler.getToolbox(this, CHART_EDITOR_TOOLBOX_DIFFICULTY_LAYOUT);
+      var difficultyToolbox:Null<CollapsibleDialog> = ChartEditorToolboxHandler.getToolbox(this, CHART_EDITOR_TOOLBOX_DIFFICULTY_LAYOUT);
       if (difficultyToolbox == null) return null;
 
       treeView = difficultyToolbox.findComponent('difficultyToolboxTree');
@@ -3428,7 +3429,8 @@ class ChartEditorState extends HaxeUIState
    */
   function refreshSongMetadataToolbox():Void
   {
-    var toolbox:CollapsibleDialog = ChartEditorToolboxHandler.getToolbox(this, CHART_EDITOR_TOOLBOX_METADATA_LAYOUT);
+    var toolbox:Null<CollapsibleDialog> = ChartEditorToolboxHandler.getToolbox(this, CHART_EDITOR_TOOLBOX_METADATA_LAYOUT);
+    if (toolbox == null) return;
 
     var inputSongName:Null<TextField> = toolbox.findComponent('inputSongName', TextField);
     if (inputSongName != null) inputSongName.value = currentSongMetadata.songName;
diff --git a/source/funkin/ui/debug/charting/ChartEditorThemeHandler.hx b/source/funkin/ui/debug/charting/ChartEditorThemeHandler.hx
index fb867c1fd..0916a1bea 100644
--- a/source/funkin/ui/debug/charting/ChartEditorThemeHandler.hx
+++ b/source/funkin/ui/debug/charting/ChartEditorThemeHandler.hx
@@ -20,6 +20,7 @@ enum ChartEditorTheme
 /**
  * Static functions which handle building themed UI elements for a provided ChartEditorState.
  */
+@:nullSafety
 class ChartEditorThemeHandler
 {
   // TODO: There's probably a better system of organization for these colors.
@@ -97,6 +98,7 @@ class ChartEditorThemeHandler
    */
   static function updateBackground(state:ChartEditorState):Void
   {
+    if (state.menuBG == null) return;
     state.menuBG.color = switch (state.currentTheme)
     {
       case ChartEditorTheme.Light: BACKGROUND_COLOR_LIGHT;
diff --git a/source/funkin/ui/debug/charting/ChartEditorToolboxHandler.hx b/source/funkin/ui/debug/charting/ChartEditorToolboxHandler.hx
index 152615568..f67a69112 100644
--- a/source/funkin/ui/debug/charting/ChartEditorToolboxHandler.hx
+++ b/source/funkin/ui/debug/charting/ChartEditorToolboxHandler.hx
@@ -39,6 +39,7 @@ enum ChartEditorToolMode
 /**
  * Static functions which handle building themed UI elements for a provided ChartEditorState.
  */
+@:nullSafety
 @:allow(funkin.ui.debug.charting.ChartEditorState)
 class ChartEditorToolboxHandler
 {
@@ -56,7 +57,7 @@ class ChartEditorToolboxHandler
 
   public static function showToolbox(state:ChartEditorState, id:String):Void
   {
-    var toolbox:CollapsibleDialog = state.activeToolboxes.get(id);
+    var toolbox:Null<CollapsibleDialog> = state.activeToolboxes.get(id);
 
     if (toolbox == null) toolbox = initToolbox(state, id);
 
@@ -95,7 +96,7 @@ class ChartEditorToolboxHandler
 
   public static function hideToolbox(state:ChartEditorState, id:String):Void
   {
-    var toolbox:CollapsibleDialog = state.activeToolboxes.get(id);
+    var toolbox:Null<CollapsibleDialog> = state.activeToolboxes.get(id);
 
     if (toolbox == null) toolbox = initToolbox(state, id);
 
@@ -134,7 +135,7 @@ class ChartEditorToolboxHandler
 
   public static function minimizeToolbox(state:ChartEditorState, id:String):Void
   {
-    var toolbox:CollapsibleDialog = state.activeToolboxes.get(id);
+    var toolbox:Null<CollapsibleDialog> = state.activeToolboxes.get(id);
 
     if (toolbox == null) return;
 
@@ -143,16 +144,16 @@ class ChartEditorToolboxHandler
 
   public static function maximizeToolbox(state:ChartEditorState, id:String):Void
   {
-    var toolbox:CollapsibleDialog = state.activeToolboxes.get(id);
+    var toolbox:Null<CollapsibleDialog> = state.activeToolboxes.get(id);
 
     if (toolbox == null) return;
 
     toolbox.minimized = false;
   }
 
-  public static function initToolbox(state:ChartEditorState, id:String):CollapsibleDialog
+  public static function initToolbox(state:ChartEditorState, id:String):Null<CollapsibleDialog>
   {
-    var toolbox:CollapsibleDialog = null;
+    var toolbox:Null<CollapsibleDialog> = null;
     switch (id)
     {
       case ChartEditorState.CHART_EDITOR_TOOLBOX_TOOLS_LAYOUT:
@@ -193,9 +194,9 @@ class ChartEditorToolboxHandler
    * @param id The asset ID of the toolbox layout.
    * @return The toolbox.
    */
-  public static function getToolbox(state:ChartEditorState, id:String):CollapsibleDialog
+  public static function getToolbox(state:ChartEditorState, id:String):Null<CollapsibleDialog>
   {
-    var toolbox:CollapsibleDialog = state.activeToolboxes.get(id);
+    var toolbox:Null<CollapsibleDialog> = state.activeToolboxes.get(id);
 
     // Initialize the toolbox without showing it.
     if (toolbox == null) toolbox = initToolbox(state, id);
@@ -205,7 +206,7 @@ class ChartEditorToolboxHandler
     return toolbox;
   }
 
-  static function buildToolboxToolsLayout(state:ChartEditorState):CollapsibleDialog
+  static function buildToolboxToolsLayout(state:ChartEditorState):Null<CollapsibleDialog>
   {
     var toolbox:CollapsibleDialog = cast state.buildComponent(ChartEditorState.CHART_EDITOR_TOOLBOX_TOOLS_LAYOUT);
 
@@ -219,7 +220,8 @@ class ChartEditorToolboxHandler
       state.setUICheckboxSelected('menubarItemToggleToolboxTools', false);
     }
 
-    var toolsGroup:Group = toolbox.findComponent('toolboxToolsGroup', Group);
+    var toolsGroup:Null<Group> = toolbox.findComponent('toolboxToolsGroup', Group);
+    if (toolsGroup == null) throw 'ChartEditorToolboxHandler.buildToolboxToolsLayout() - Could not find toolboxToolsGroup component.';
 
     if (toolsGroup == null) return null;
 
@@ -242,7 +244,7 @@ class ChartEditorToolboxHandler
 
   static function onHideToolboxTools(state:ChartEditorState, toolbox:CollapsibleDialog):Void {}
 
-  static function buildToolboxNoteDataLayout(state:ChartEditorState):CollapsibleDialog
+  static function buildToolboxNoteDataLayout(state:ChartEditorState):Null<CollapsibleDialog>
   {
     var toolbox:CollapsibleDialog = cast state.buildComponent(ChartEditorState.CHART_EDITOR_TOOLBOX_NOTEDATA_LAYOUT);
 
@@ -256,9 +258,13 @@ class ChartEditorToolboxHandler
       state.setUICheckboxSelected('menubarItemToggleToolboxNotes', false);
     }
 
-    var toolboxNotesNoteKind:DropDown = toolbox.findComponent('toolboxNotesNoteKind', DropDown);
-    var toolboxNotesCustomKindLabel:Label = toolbox.findComponent('toolboxNotesCustomKindLabel', Label);
-    var toolboxNotesCustomKind:TextField = toolbox.findComponent('toolboxNotesCustomKind', TextField);
+    var toolboxNotesNoteKind:Null<DropDown> = toolbox.findComponent('toolboxNotesNoteKind', DropDown);
+    if (toolboxNotesNoteKind == null) throw 'ChartEditorToolboxHandler.buildToolboxNoteDataLayout() - Could not find toolboxNotesNoteKind component.';
+    var toolboxNotesCustomKindLabel:Null<Label> = toolbox.findComponent('toolboxNotesCustomKindLabel', Label);
+    if (toolboxNotesCustomKindLabel == null)
+      throw 'ChartEditorToolboxHandler.buildToolboxNoteDataLayout() - Could not find toolboxNotesCustomKindLabel component.';
+    var toolboxNotesCustomKind:Null<TextField> = toolbox.findComponent('toolboxNotesCustomKind', TextField);
+    if (toolboxNotesCustomKind == null) throw 'ChartEditorToolboxHandler.buildToolboxNoteDataLayout() - Could not find toolboxNotesCustomKind component.';
 
     toolboxNotesNoteKind.onChange = function(event:UIEvent) {
       var isCustom:Bool = (event.data.id == '~CUSTOM~');
@@ -290,7 +296,7 @@ class ChartEditorToolboxHandler
 
   static function onHideToolboxNoteData(state:ChartEditorState, toolbox:CollapsibleDialog):Void {}
 
-  static function buildToolboxEventDataLayout(state:ChartEditorState):CollapsibleDialog
+  static function buildToolboxEventDataLayout(state:ChartEditorState):Null<CollapsibleDialog>
   {
     var toolbox:CollapsibleDialog = cast state.buildComponent(ChartEditorState.CHART_EDITOR_TOOLBOX_EVENTDATA_LAYOUT);
 
@@ -304,8 +310,10 @@ class ChartEditorToolboxHandler
       state.setUICheckboxSelected('menubarItemToggleToolboxEvents', false);
     }
 
-    var toolboxEventsEventKind:DropDown = toolbox.findComponent('toolboxEventsEventKind', DropDown);
-    var toolboxEventsDataGrid:Grid = toolbox.findComponent('toolboxEventsDataGrid', Grid);
+    var toolboxEventsEventKind:Null<DropDown> = toolbox.findComponent('toolboxEventsEventKind', DropDown);
+    if (toolboxEventsEventKind == null) throw 'ChartEditorToolboxHandler.buildToolboxEventDataLayout() - Could not find toolboxEventsEventKind component.';
+    var toolboxEventsDataGrid:Null<Grid> = toolbox.findComponent('toolboxEventsDataGrid', Grid);
+    if (toolboxEventsDataGrid == null) throw 'ChartEditorToolboxHandler.buildToolboxEventDataLayout() - Could not find toolboxEventsDataGrid component.';
 
     toolboxEventsEventKind.dataSource = new ArrayDataSource();
 
@@ -349,6 +357,8 @@ class ChartEditorToolboxHandler
 
     for (field in schema)
     {
+      if (field == null) continue;
+
       // Add a label.
       var label:Label = new Label();
       label.text = field.title;
@@ -360,33 +370,36 @@ class ChartEditorToolboxHandler
         case INTEGER:
           var numberStepper:NumberStepper = new NumberStepper();
           numberStepper.id = field.name;
-          numberStepper.step = field.step == null ? 1.0 : field.step;
-          numberStepper.min = field.min;
-          numberStepper.max = field.max;
-          numberStepper.value = field.defaultValue;
+          numberStepper.step = field.step ?? 1.0;
+          numberStepper.min = field.min ?? 0.0;
+          numberStepper.max = field.max ?? 10.0;
+          if (field.defaultValue != null) numberStepper.value = field.defaultValue;
           input = numberStepper;
         case FLOAT:
           var numberStepper:NumberStepper = new NumberStepper();
           numberStepper.id = field.name;
-          numberStepper.step = field.step == null ? 0.1 : field.step;
-          numberStepper.min = field.min;
-          numberStepper.max = field.max;
-          numberStepper.value = field.defaultValue;
+          numberStepper.step = field.step ?? 0.1;
+          numberStepper.min = field.min ?? 0.0;
+          numberStepper.max = field.max ?? 1.0;
+          if (field.defaultValue != null) numberStepper.value = field.defaultValue;
           input = numberStepper;
         case BOOL:
           var checkBox:CheckBox = new CheckBox();
           checkBox.id = field.name;
-          checkBox.selected = field.defaultValue;
+          if (field.defaultValue != null) checkBox.selected = field.defaultValue;
           input = checkBox;
         case ENUM:
           var dropDown:DropDown = new DropDown();
           dropDown.id = field.name;
           dropDown.dataSource = new ArrayDataSource();
 
+          if (field.keys == null) throw 'Field "${field.name}" is of Enum type but has no keys.';
+
           // Add entries to the dropdown.
+
           for (optionName in field.keys.keys())
           {
-            var optionValue:String = field.keys.get(optionName);
+            var optionValue:Null<String> = field.keys.get(optionName);
             trace('$optionName : $optionValue');
             dropDown.dataSource.add({value: optionValue, text: optionName});
           }
@@ -397,7 +410,7 @@ class ChartEditorToolboxHandler
         case STRING:
           input = new TextField();
           input.id = field.name;
-          input.text = field.defaultValue;
+          if (field.defaultValue != null) input.text = field.defaultValue;
         default:
           // Unknown type. Display a label so we know what it is.
           input = new Label();
@@ -417,7 +430,7 @@ class ChartEditorToolboxHandler
     }
   }
 
-  static function buildToolboxDifficultyLayout(state:ChartEditorState):CollapsibleDialog
+  static function buildToolboxDifficultyLayout(state:ChartEditorState):Null<CollapsibleDialog>
   {
     var toolbox:CollapsibleDialog = cast state.buildComponent(ChartEditorState.CHART_EDITOR_TOOLBOX_DIFFICULTY_LAYOUT);
 
@@ -431,11 +444,20 @@ class ChartEditorToolboxHandler
       state.setUICheckboxSelected('menubarItemToggleToolboxDifficulty', false);
     }
 
-    var difficultyToolboxSaveMetadata:Button = toolbox.findComponent('difficultyToolboxSaveMetadata', Button);
-    var difficultyToolboxSaveChart:Button = toolbox.findComponent('difficultyToolboxSaveChart', Button);
-    var difficultyToolboxSaveAll:Button = toolbox.findComponent('difficultyToolboxSaveAll', Button);
-    var difficultyToolboxLoadMetadata:Button = toolbox.findComponent('difficultyToolboxLoadMetadata', Button);
-    var difficultyToolboxLoadChart:Button = toolbox.findComponent('difficultyToolboxLoadChart', Button);
+    var difficultyToolboxSaveMetadata:Null<Button> = toolbox.findComponent('difficultyToolboxSaveMetadata', Button);
+    if (difficultyToolboxSaveMetadata == null)
+      throw 'ChartEditorToolboxHandler.buildToolboxDifficultyLayout() - Could not find difficultyToolboxSaveMetadata component.';
+    var difficultyToolboxSaveChart:Null<Button> = toolbox.findComponent('difficultyToolboxSaveChart', Button);
+    if (difficultyToolboxSaveChart == null)
+      throw 'ChartEditorToolboxHandler.buildToolboxDifficultyLayout() - Could not find difficultyToolboxSaveChart component.';
+    var difficultyToolboxSaveAll:Null<Button> = toolbox.findComponent('difficultyToolboxSaveAll', Button);
+    if (difficultyToolboxSaveAll == null) throw 'ChartEditorToolboxHandler.buildToolboxDifficultyLayout() - Could not find difficultyToolboxSaveAll component.';
+    var difficultyToolboxLoadMetadata:Null<Button> = toolbox.findComponent('difficultyToolboxLoadMetadata', Button);
+    if (difficultyToolboxLoadMetadata == null)
+      throw 'ChartEditorToolboxHandler.buildToolboxDifficultyLayout() - Could not find difficultyToolboxLoadMetadata component.';
+    var difficultyToolboxLoadChart:Null<Button> = toolbox.findComponent('difficultyToolboxLoadChart', Button);
+    if (difficultyToolboxLoadChart == null)
+      throw 'ChartEditorToolboxHandler.buildToolboxDifficultyLayout() - Could not find difficultyToolboxLoadChart component.';
 
     difficultyToolboxSaveMetadata.onClick = function(event:UIEvent) {
       SongSerializer.exportSongMetadata(state.currentSongMetadata, state.currentSongId);
@@ -472,16 +494,18 @@ class ChartEditorToolboxHandler
   static function onShowToolboxDifficulty(state:ChartEditorState, toolbox:CollapsibleDialog):Void
   {
     // Update the selected difficulty when reopening the toolbox.
-    var treeView:TreeView = toolbox.findComponent('difficultyToolboxTree');
+    var treeView:Null<TreeView> = toolbox.findComponent('difficultyToolboxTree');
     if (treeView == null) return;
 
-    treeView.selectedNode = state.getCurrentTreeDifficultyNode(treeView);
+    var current = state.getCurrentTreeDifficultyNode(treeView);
+    if (current == null) return;
+    treeView.selectedNode = current;
     trace('selected node: ${treeView.selectedNode}');
   }
 
   static function onHideToolboxDifficulty(state:ChartEditorState, toolbox:CollapsibleDialog):Void {}
 
-  static function buildToolboxMetadataLayout(state:ChartEditorState):CollapsibleDialog
+  static function buildToolboxMetadataLayout(state:ChartEditorState):Null<CollapsibleDialog>
   {
     var toolbox:CollapsibleDialog = cast state.buildComponent(ChartEditorState.CHART_EDITOR_TOOLBOX_METADATA_LAYOUT);
 
@@ -495,7 +519,8 @@ class ChartEditorToolboxHandler
       state.setUICheckboxSelected('menubarItemToggleToolboxMetadata', false);
     }
 
-    var inputSongName:TextField = toolbox.findComponent('inputSongName', TextField);
+    var inputSongName:Null<TextField> = toolbox.findComponent('inputSongName', TextField);
+    if (inputSongName == null) throw 'ChartEditorToolboxHandler.buildToolboxMetadataLayout() - Could not find inputSongName component.';
     inputSongName.onChange = function(event:UIEvent) {
       var valid:Bool = event.target.text != null && event.target.text != '';
 
@@ -506,12 +531,13 @@ class ChartEditorToolboxHandler
       }
       else
       {
-        state.currentSongMetadata.songName = null;
+        state.currentSongMetadata.songName = '';
       }
     };
     inputSongName.value = state.currentSongMetadata.songName;
 
-    var inputSongArtist:TextField = toolbox.findComponent('inputSongArtist', TextField);
+    var inputSongArtist:Null<TextField> = toolbox.findComponent('inputSongArtist', TextField);
+    if (inputSongArtist == null) throw 'ChartEditorToolboxHandler.buildToolboxMetadataLayout() - Could not find inputSongArtist component.';
     inputSongArtist.onChange = function(event:UIEvent) {
       var valid:Bool = event.target.text != null && event.target.text != '';
 
@@ -522,12 +548,13 @@ class ChartEditorToolboxHandler
       }
       else
       {
-        state.currentSongMetadata.artist = null;
+        state.currentSongMetadata.artist = '';
       }
     };
     inputSongArtist.value = state.currentSongMetadata.artist;
 
-    var inputStage:DropDown = toolbox.findComponent('inputStage', DropDown);
+    var inputStage:Null<DropDown> = toolbox.findComponent('inputStage', DropDown);
+    if (inputStage == null) throw 'ChartEditorToolboxHandler.buildToolboxMetadataLayout() - Could not find inputStage component.';
     inputStage.onChange = function(event:UIEvent) {
       var valid:Bool = event.data != null && event.data.id != null;
 
@@ -538,14 +565,16 @@ class ChartEditorToolboxHandler
     };
     inputStage.value = state.currentSongMetadata.playData.stage;
 
-    var inputNoteSkin:DropDown = toolbox.findComponent('inputNoteSkin', DropDown);
+    var inputNoteSkin:Null<DropDown> = toolbox.findComponent('inputNoteSkin', DropDown);
+    if (inputNoteSkin == null) throw 'ChartEditorToolboxHandler.buildToolboxMetadataLayout() - Could not find inputNoteSkin component.';
     inputNoteSkin.onChange = function(event:UIEvent) {
       if ((event?.data?.id ?? null) == null) return;
       state.currentSongMetadata.playData.noteSkin = event.data.id;
     };
     inputNoteSkin.value = state.currentSongMetadata.playData.noteSkin;
 
-    var inputBPM:NumberStepper = toolbox.findComponent('inputBPM', NumberStepper);
+    var inputBPM:Null<NumberStepper> = toolbox.findComponent('inputBPM', NumberStepper);
+    if (inputBPM == null) throw 'ChartEditorToolboxHandler.buildToolboxMetadataLayout() - Could not find inputBPM component.';
     inputBPM.onChange = function(event:UIEvent) {
       if (event.value == null || event.value <= 0) return;
 
@@ -565,9 +594,11 @@ class ChartEditorToolboxHandler
     };
     inputBPM.value = state.currentSongMetadata.timeChanges[0].bpm;
 
-    var labelScrollSpeed:Label = toolbox.findComponent('labelScrollSpeed', Label);
+    var labelScrollSpeed:Null<Label> = toolbox.findComponent('labelScrollSpeed', Label);
+    if (labelScrollSpeed == null) throw 'ChartEditorToolboxHandler.buildToolboxMetadataLayout() - Could not find labelScrollSpeed component.';
 
-    var inputScrollSpeed:Slider = toolbox.findComponent('inputScrollSpeed', Slider);
+    var inputScrollSpeed:Null<Slider> = toolbox.findComponent('inputScrollSpeed', Slider);
+    if (inputScrollSpeed == null) throw 'ChartEditorToolboxHandler.buildToolboxMetadataLayout() - Could not find inputScrollSpeed component.';
     inputScrollSpeed.onChange = function(event:UIEvent) {
       var valid:Bool = event.target.value != null && event.target.value > 0;
 
@@ -585,10 +616,12 @@ class ChartEditorToolboxHandler
     inputScrollSpeed.value = state.currentSongChartScrollSpeed;
     labelScrollSpeed.text = 'Scroll Speed: ${state.currentSongChartScrollSpeed}x';
 
-    var frameVariation:Frame = toolbox.findComponent('frameVariation', Frame);
+    var frameVariation:Null<Frame> = toolbox.findComponent('frameVariation', Frame);
+    if (frameVariation == null) throw 'ChartEditorToolboxHandler.buildToolboxMetadataLayout() - Could not find frameVariation component.';
     frameVariation.text = 'Variation: ${state.selectedVariation.toTitleCase()}';
 
-    var frameDifficulty:Frame = toolbox.findComponent('frameDifficulty', Frame);
+    var frameDifficulty:Null<Frame> = toolbox.findComponent('frameDifficulty', Frame);
+    if (frameDifficulty == null) throw 'ChartEditorToolboxHandler.buildToolboxMetadataLayout() - Could not find frameDifficulty component.';
     frameDifficulty.text = 'Difficulty: ${state.selectedDifficulty.toTitleCase()}';
 
     return toolbox;
@@ -601,7 +634,7 @@ class ChartEditorToolboxHandler
 
   static function onHideToolboxMetadata(state:ChartEditorState, toolbox:CollapsibleDialog):Void {}
 
-  static function buildToolboxCharactersLayout(state:ChartEditorState):CollapsibleDialog
+  static function buildToolboxCharactersLayout(state:ChartEditorState):Null<CollapsibleDialog>
   {
     var toolbox:CollapsibleDialog = cast state.buildComponent(ChartEditorState.CHART_EDITOR_TOOLBOX_CHARACTERS_LAYOUT);
 
@@ -622,7 +655,7 @@ class ChartEditorToolboxHandler
 
   static function onHideToolboxCharacters(state:ChartEditorState, toolbox:CollapsibleDialog):Void {}
 
-  static function buildToolboxPlayerPreviewLayout(state:ChartEditorState):CollapsibleDialog
+  static function buildToolboxPlayerPreviewLayout(state:ChartEditorState):Null<CollapsibleDialog>
   {
     var toolbox:CollapsibleDialog = cast state.buildComponent(ChartEditorState.CHART_EDITOR_TOOLBOX_PLAYER_PREVIEW_LAYOUT);
 
@@ -636,7 +669,8 @@ class ChartEditorToolboxHandler
       state.setUICheckboxSelected('menubarItemToggleToolboxPlayerPreview', false);
     }
 
-    var charPlayer:CharacterPlayer = toolbox.findComponent('charPlayer');
+    var charPlayer:Null<CharacterPlayer> = toolbox.findComponent('charPlayer');
+    if (charPlayer == null) throw 'ChartEditorToolboxHandler.buildToolboxPlayerPreviewLayout() - Could not find charPlayer component.';
     // TODO: We need to implement character swapping in ChartEditorState.
     charPlayer.loadCharacter('bf');
     charPlayer.characterType = CharacterType.BF;
@@ -650,7 +684,7 @@ class ChartEditorToolboxHandler
 
   static function onHideToolboxPlayerPreview(state:ChartEditorState, toolbox:CollapsibleDialog):Void {}
 
-  static function buildToolboxOpponentPreviewLayout(state:ChartEditorState):CollapsibleDialog
+  static function buildToolboxOpponentPreviewLayout(state:ChartEditorState):Null<CollapsibleDialog>
   {
     var toolbox:CollapsibleDialog = cast state.buildComponent(ChartEditorState.CHART_EDITOR_TOOLBOX_OPPONENT_PREVIEW_LAYOUT);
 
@@ -664,7 +698,8 @@ class ChartEditorToolboxHandler
       state.setUICheckboxSelected('menubarItemToggleToolboxOpponentPreview', false);
     }
 
-    var charPlayer:CharacterPlayer = toolbox.findComponent('charPlayer');
+    var charPlayer:Null<CharacterPlayer> = toolbox.findComponent('charPlayer');
+    if (charPlayer == null) throw 'ChartEditorToolboxHandler.buildToolboxOpponentPreviewLayout() - Could not find charPlayer component.';
     // TODO: We need to implement character swapping in ChartEditorState.
     charPlayer.loadCharacter('dad');
     charPlayer.characterType = CharacterType.DAD;
diff --git a/source/funkin/ui/haxeui/components/CharacterPlayer.hx b/source/funkin/ui/haxeui/components/CharacterPlayer.hx
index daeb17fc9..66b94bfa2 100644
--- a/source/funkin/ui/haxeui/components/CharacterPlayer.hx
+++ b/source/funkin/ui/haxeui/components/CharacterPlayer.hx
@@ -56,7 +56,7 @@ class CharacterPlayer extends Box
     return value;
   }
 
-  public var charName(get, null):String;
+  public var charName(get, never):String;
 
   function get_charName():String
   {
diff --git a/source/funkin/util/Constants.hx b/source/funkin/util/Constants.hx
index 71cfe7b8e..b454ca429 100644
--- a/source/funkin/util/Constants.hx
+++ b/source/funkin/util/Constants.hx
@@ -20,7 +20,7 @@ class Constants
    * The current version number of the game.
    * Modify this in the `project.xml` file.
    */
-  public static var VERSION(get, null):String;
+  public static var VERSION(get, never):String;
 
   /**
    * A suffix to add to the game version.