better panic message

src/lib.rs

@@ -23,8 +23,8 @@ impl<'a, T> Deref for MaybeOwned<'a, T> {
 
     fn deref(&self) -> &Self::Target {
         match self {
-            Self::Owned(v) => &v,
-            Self::Borrowed(v) => v
+            Self::Owned(v) => v,
+            Self::Borrowed(v) => v,
         }
     }
 }
@@ -93,7 +93,11 @@ impl<'a> Parse for SyntectParser<'a> {
                     &captures[2],
                     &self.syntax_set,
                     &syntax,
-                    &self.theme_set.themes[self.theme],
+                    &self
+                        .theme_set
+                        .themes
+                        .get(self.theme)
+                        .expect(format!("couldn't find theme \"{}\"", self.theme).as_str()),
                 )
                 .unwrap()
             })