src/vs/workbench/api/browser/mainThreadCustomEditors.ts/MainThreadCustomEditorModel/dispose
class MainThreadCustomEditorModel:	override dispose() {
		if (this._editable) {
			this._undoService.removeElements(this._editorResource);
		}

		this._proxy.$disposeCustomDocument(this._editorResource, this._viewType);

		super.dispose();
	}