我这里有一个简单的express应用程序，为了使mongoose.connection.getClient（）工作，我需要有一个已经建立的数据库连接。把app.use（session（）），app.use（passport.initialize（））; app.use（passport.session（））;里面，然后是 Mongoose ，连接？
所以基本上我是在问这个代码结构是否正确

import express from "express";
import mongoose from "mongoose";
import passport from "passport";
import dotenv from "dotenv";
import session from "express-session";
import MongoStore from "connect-mongo";
import routes from "./routes/index.js";
import "./config/passport.js";

//Configurations
const app = express();
dotenv.config();

//Middleware
app.use(express.json());

//Database setup
mongoose.connect(process.env.MONGO_URL, { useNewUrlParser: true, useUnifiedTopology: true })
   .then(() => {
      console.log("Database connection has been established");

      //Auth middleware
      app.use(session({
         secret: "secret",
         resave: false,
         saveUninitialized: false,
         store: MongoStore.create({ client: mongoose.connection.getClient(), collectionName: "sessions" }),
         cookie: {
            maxAge: 1000 * 60
         }
      }))
      app.use(passport.initialize());
      app.use(passport.session());

      //Server listening
      const PORT = process.env.PORT || 6001;
      app.listen(PORT, () => { console.log(`App is listeting on PORT ${PORT}`); });

   })
   .catch((err) => { console.log(`Database connection error: ${err}`); })

//Router
app.use(routes);

//Error handler
app.use((err, req, res, next) => {
   res.json({error: "Error:("})
})