docs: function immutableAppHttpError (code, msg, data, cookies, headers) {
      // default to 400 application error
      if (!code) {
          code = 400
      }
      // set msg based on code if not set
      if (!msg) {
          msg = httpErrors[code] || 'Unspecified Error'
      }
      // create new error
      var err = new Error(msg)
      err.code = code
      err.data = data
      err.cookies = cookies
      err.headers = headers
      // throw error which will be handled by application framework
      throw err
  }