anchor.diff:            enablePreview: options.webPreview,
             summaryPath: options.summary);
         fixCodeProcessor.registerCodeTask(nonNullableFix);
  +
         try {
           await fixCodeProcessor.runFirstPhase();
  +        fixCodeProcessor._progressBar.clear();
           _checkForErrors();
         } on StateError catch (e) {
           logger.stdout(e.toString());
  
positive.code: 
    final Set<String> pathsToProcess;
  
    final MigrationCli _migrationCli;
  
    _FixCodeProcessor(this.context, this._migrationCli)
  
negative.code:             .toSet();
  
    /// Call the supplied [process] function to process each compilation unit.
    Future<void> processResources(
        Future<void> Function(ResolvedUnitResult result) process) async {
      var driver = context.currentSession;
      var pathsProcessed = <String>{};
  