我正在关注本教程，尝试将一些函数部署到 Firebase，我可以成功地将它们部署到我的项目 ID。在提供的 URL 上访问以下函数时，出现错误：无法处理请求
// The Cloud Functions for Firebase SDK to create Cloud Functions and setup
triggers.
const functions = require('firebase-functions');
// The Firebase Admin SDK to access the Firebase Realtime Database.
const admin = require ('firebase-admin');
admin.initializeApp(functions.config().firebase);
exports.date = functions.https.onRequest((req, res) => {
let format = req.query.format;
const date = moment().format();
res.status(200).json({ date: date});
})
我的 Firebase 控制台在执行时记录此内容：
ReferenceError: moment is not defined
at exports.date.functions.https.onRequest (/user_code/index.js:10:24)
at cloudFunction (/user_code/node_modules/firebase-
functions/lib/providers/https.js:26:41)
at /var/tmp/worker/worker.js:635:7
at /var/tmp/worker/worker.js:619:9
at …