Apply @:nullSafety to chart editor classes.

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>;
@@ -679,6 +692,7 @@ class CutItemsCommand implements ChartEditorCommand
   }
 }
 
+@:nullSafety
 class FlipNotesCommand implements ChartEditorCommand
 {
   var notes:Array<SongNoteData>;
@@ -729,6 +743,7 @@ class FlipNotesCommand implements ChartEditorCommand
   }
 }
 
+@:nullSafety
 class PasteItemsCommand implements ChartEditorCommand
 {
   var targetTimestamp:Float;
@@ -787,6 +802,7 @@ class PasteItemsCommand implements ChartEditorCommand
   }
 }
 
+@:nullSafety
 class ExtendNoteLengthCommand implements ChartEditorCommand
 {
   var note:SongNoteData;

source/funkin/ui/debug/charting/ChartEditorDialogHandler.hx

@@ -40,6 +40,7 @@ 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');

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';

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
 {
   /**

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
 {
   //

source/funkin/ui/debug/charting/ChartEditorNoteSprite.hx

@@ -11,6 +11,7 @@ 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
 {
   /**

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.