anchor.diff:        api.rootUrl = serverUrl;
         window.localStorage['null_safety'] = 'false';
       }
  +
  +    updateVersion();
   
       QueryParams.nullSafety = enabled;
   
  
positive.code: 
      docHandler = DocHandler(editor, _context);
  
      dartServices.version().then((VersionResponse version) {
        // "Based on Flutter 1.19.0-4.1.pre Dart SDK 2.8.4"
        var versionText = 'Based on Flutter ${version.flutterVersion}'
            ' Dart SDK ${version.sdkVersionFull}';
        querySelector('#dartpad-version').text = versionText;
      }).catchError((e) => null);
  
      analysisResultsController = AnalysisResultsController(
          DElement(querySelector('#issues')),
  
negative.code:       });
  
      _finishedInit();
    }
  
    void updateVersion() {
      dartServices.version().then((VersionResponse version) {
        // "Based on Flutter 1.19.0-4.1.pre Dart SDK 2.8.4"
        var versionText = 'Based on Flutter ${version.flutterVersion}'
            ' Dart SDK ${version.sdkVersionFull}';
        querySelector('#dartpad-version').text = versionText;
      }).catchError((e) => null);
    }
  
    void _finishedInit() {
  