anchor.diff:  
     /// Log the given message with the given tag.
     void _log(String tag, String message) {
  -    if (_instrumentationLogger != null) {
  -      _instrumentationLogger!.log(_join([tag, message]));
  -    }
  +    _instrumentationLogger.log(_join([tag, message]));
     }
   
     /// Convert the given [object] to a string.
  
positive.code:   static const String TAG_WATCH_EVENT = 'Watch';
  
    /// A logger used to log instrumentation in string format.
    final InstrumentationLogger? _instrumentationLogger;
  
    /// Initialize a newly created instrumentation service to communicate with the
    /// given [_instrumentationLogger].
  
negative.code:   @override
    void logPluginError(
        PluginData plugin, String code, String message, String stackTrace) {
      List<String> fields = <String>[TAG_PLUGIN_ERROR, code, message, stackTrace];
      plugin.addToFields(fields);
      _instrumentationLogger.log(_join(fields));
    }
  
    @override
    void logPluginException(
        PluginData plugin, dynamic exception, StackTrace? stackTrace) {
      List<String> fields = <String>[
        TAG_PLUGIN_EXCEPTION,
        _toString(exception),
        _toString(stackTrace)
      ];
      plugin.addToFields(fields);
      _instrumentationLogger.log(_join(fields));
    }
  
    @override
    void logPluginNotification(String pluginId, String notification) {
      _instrumentationLogger
          .log(_join([TAG_PLUGIN_NOTIFICATION, notification, pluginId, '', '']));
    }
  
    @override
    void logPluginRequest(String pluginId, String request) {
      _instrumentationLogger
          .log(_join([TAG_PLUGIN_REQUEST, request, pluginId, '', '']));
    }
  
    @override
    void logPluginResponse(String pluginId, String response) {
      _instrumentationLogger
          .log(_join([TAG_PLUGIN_RESPONSE, response, pluginId, '', '']));
    }
  
    @override
    void logPluginTimeout(PluginData plugin, String request) {
      List<String> fields = <String>[TAG_PLUGIN_TIMEOUT, request];
      plugin.addToFields(fields);
      _instrumentationLogger.log(_join(fields));
    }
  
    @override
  