anchor.diff:      // Set up CodeMirror
       editor = (editorFactory as CodeMirrorFactory)
           .createFromElement(_editorHost, options: codeMirrorOptions)
  -      ..theme = 'darkpad'
  -      ..mode = 'dart'
  -      ..showLineNumbers = true;
  +          ..theme = 'darkpad'
  +          ..mode = 'dart'
  +          ..showLineNumbers = true;
   
       context = WorkshopDartSourceProvider(editor);
       docHandler = DocHandler(editor, context);
  
positive.code:   late final MDCButton editorUiOutputTab;
    late final MDCButton editorConsoleTab;
    late final MDCButton editorDocsTab;
    final _nullSafetyEnabled = true;
  
    WorkshopUi() {
      _init();
  
negative.code:       querySelector('#editor-panel-footer') as DivElement;
  
    @override
    bool get nullSafetyEnabled => true;
  
    /// Whether null safety was enabled for the previous execution.
    @override
    bool get nullSafetyWasPreviouslyEnabled => true;
  
    @override
    set nullSafetyEnabled(bool v) {
  