expressjs中的中间件函数错误

我无法在终端中运行节点主文件 我使用车把作为模板引擎

得到这个奇怪的错误 我没有npm安装所有需要的依赖项。但仍然会出现这个错误。

/home/mohsin/Desktop/mohsin/react/react-web-app/node_modules/express/lib/application.js:210
throw new TypeError('app.use() requires a middleware function')
^

TypeError: app.use() requires a middleware function

这是错误截图,请查看 https://i.imgur.com/c6zoaA6.png

我的应用。js文件

const express = require('express');
const path = require('path');
const bodyParser = require('body-parser');
const exphbs = require('express-handlebars');
const expressValidator = require('express-validator');
const flash = require('connect-flash');
const session = require('express-sessions');
const passport = require('passport');
const mongoose = require('mongoose');

// Port env
const port = 3000;

// Route files
 const index = require('./routes/index');
const user = require('./routes/user');

  // Init App
  const app = express();

  // View Engine
    app.engine('handlebars', exphbs({defaultLayout: 'main'}));
   app.set('view engine', 'handlebars');

   // Static Folder
   app.use(express.static(path.join(__dirname, 'public')));

   // Body parser middleware
    app.use(bodyParser.json());
    app.use(bodyParser.urlencoded({ extended: false}));

     // Express Session
      app.use(session({
secret: 'secret',
saveUninitialized: true,
resave: true
 }));



 // Start server
 app.use('/', index);
 app.use('/user', user);

  // Start Server
 app.listen(port, () => {
 console.log('Server started on port '+port);
 });