code: private void serveError(Status status, HTTPTrackerErrorMessage error, RequestHandler requestHandler) throws IOException {
      requestHandler.serveResponse(status.getCode(), status.getDescription(), error.getData());
    }
docs: Write a {@link HTTPTrackerErrorMessage} to the response with the given
  HTTP status code.
  
  @param status The HTTP status code to return.
  @param error  The error reported by the tracker.