anchor.diff:  
       _overrideNextRouteGist = null;
   
  +    _gistIdInProgress = gistId;
       gistLoader.loadGist(gistId).then((Gist gist) {
         _editableGist.setBackingGist(gist);
   
  
positive.code:   }
  
    void _showGist(String gistId) {
      // Don't auto-run if we're re-loading some unsaved edits; the gist might
      // have halting issues (#384).
      var loadedFromSaved = false;
  
negative.code:       MDCSwitch(querySelector('#null-safety-switch'));
    final Element? _channelSwitch = querySelector('#channel-switch');
    MDCMenu? _channelsMenu;
    String? _gistIdInProgress;
  
    late Splitter _rightSplitter;
    bool _rightSplitterConfigured = false;
  