code: @Override
      protected void handlingError(
              EventPipeline eventProcessor, Throwable throwable) {
          eventProcessor.fire(
              new HandlingError(this, throwable), channels());
      }
docs: Implements the default behavior for handling events thrown
  by a handler. Fires a {@link HandlingError handling error} event
  for this event and the given throwable.
  
  @see HandlingError