chore: fix error when converting empty super note

packages/web/src/javascripts/Components/ChangeEditor/ChangeEditorMenu.tsx

@@ -138,7 +138,7 @@ const ChangeEditorMenu: FunctionComponent<ChangeEditorMenuProps> = ({
         return
       }
 
-      if (note.noteType === NoteType.Super) {
+      if (note.noteType === NoteType.Super && note.text.length > 0) {
         setPendingConversionItem(itemToBeSelected)
         handleDisableClickoutsideRequest?.()
         return

packages/web/src/javascripts/Components/SuperEditor/SuperNoteConverter.tsx

@@ -43,6 +43,10 @@ const SuperNoteConverter = ({
   }, [component, noteType])
 
   const convertedContent = useMemo(() => {
+    if (note.text.length === 0) {
+      return note.text
+    }
+
     return exportSuperNote(note, format)
   }, [format, note])