code: function errorPage(res, err) {
  		if (err) {
  			console.error(err.message);
  			res.send(err, {'Content-Type': 'text/plain'}, 500);
  		} else {
  			res.send(404);
  		}
  	}
docs: Displays an HTTP error response. If an error is provided, the error is displayed with a 500 error code, otherwise it's a empty 404 error.  @param res [Object] Http response @param err [String] Error message. Facultative.