anchor.diff:    late final Splitter splitter;
   
     late final Console consoleExpandController;
  -  late final DElement webOutputLabel;
  +  DElement? webOutputLabel;
     late final DElement featureMessage;
   
     late final MDCLinearProgress linearProgress;
  
positive.code:   late final TabView editorTabView;
    late final TabView testTabView;
    late final TabView solutionTabView;
    late final TabView htmlTabView;
    late final TabView cssTabView;
    late final DElement solutionTab;
    late final MDCMenu menu;
  
  
negative.code:           editorTabView.setSelected(name == 'editor');
            testTabView.setSelected(name == 'test');
            solutionTabView.setSelected(name == 'solution');
            htmlTabView?.setSelected(name == 'html');
            cssTabView?.setSelected(name == 'css');
  
            if (name == 'editor') {
              userCodeEditor.resize();
  