code: function notFound(err, res) {
    if (!(err instanceof Error) && err) {
      res = err;
    }
  
    const message = 'Not Found',
      code = 404;
  
    // hide error from user of api.
    sendDefaultResponseForCode(code, message, res);
  }
docs: All "Not Found" errors are routed like this.
  @param {Error} [err]
  @param {object} res