anchor.diff:          var version = json.expectType<String>(current['version'], 'version');
           preNullSafetyPackages[name] = version;
         }
  +    } on ProcessException catch (e) {
  +      _logger.stderr(
  +          'Warning: Could not execute `$pubPath ${pubArguments.join(' ')}`: '
  +          '"${e.message}"');
  +      // Allow the program to continue; users should be allowed to attempt to
  +      // migrate when `pub outdated` is misbehaving, or if there is a bug above.
       } on FormatException catch (e) {
         _logger.stderr('Warning: ${e.message}');
         // Allow the program to continue; users should be allowed to attempt to
  
positive.code:       }
        _logger.stderr('');
        _logger.stderr('It is highly recommended to upgrade all dependencies to '
            'versions which have migrated. Use `$_pubName outdated '
            '--mode=null-safety` to check the status of dependencies.');
        _logger.stderr('');
        _logger.stderr('Visit https://dart.dev/tools/pub/cmd/pub-outdated for '
  
negative.code:       this._directory, this._pathContext, this._logger, this._processManager);
  
    bool check() {
      var pubPath = _pathContext.join(getSdkPath(), 'bin', 'dart');
      var pubArguments = ['pub', 'outdated', '--mode=null-safety', '--json'];
      var preNullSafetyPackages = <String, String>{};
      try {
        var result = _processManager.runSync(pubPath, pubArguments,
            workingDirectory: _directory);
        if ((result.stderr as String).isNotEmpty) {
          throw FormatException(
              '`dart pub outdated --mode=null-safety` exited with exit code '
              '${result.exitCode} and stderr:\n\n${result.stderr}');
        }
        var outdatedOutput = jsonDecode(result.stdout as String);
  