Mongodb – new TypeError('Router.use() requires a middleware function but got a ' + gettype(fn))

I have tried to run this code:

const connectToMongo = require('./db')
const express = require('express')
connectToMongo();
const app = express()
const port = 3000
// Available Routes
app.use('/api/auth', require('./routes/auth'))
app.use('/api/notes', require('./routes/notes'))



app.listen(port, () => {
  console.log(`Example app listening on port ${port}`)
})

But it is giving me this error:

C:UsersCCDesktopMern courseinotebookinotebookBackendnode_modulesexpresslibrouterindex.js:469
      throw new TypeError('Router.use() requires a middleware function but got a ' + gettype(fn))
      ^

TypeError: Router.use() requires a middleware function but got a Object
    at Function.use (C:UsersCCDesktopMern courseinotebookinotebookBackendnode_modulesexpresslibrouterindex.js:469:13)
    at Function.<anonymous> (C:UsersCCDesktopMern courseinotebookinotebookBackendnode_modulesexpresslibapplication.js:227:21)
    at Array.forEach (<anonymous>)
    at Function.use (C:UsersCCDesktopMern courseinotebookinotebookBackendnode_modulesexpresslibapplication.js:224:7)
    at Object.<anonymous> (C:UsersCCDesktopMern courseinotebookinotebookBackendindex.js:7:5)      
    at Module._compile (node:internal/modules/cjs/loader:1103:14)
    at Object.Module._extensions..js (node:internal/modules/cjs/loader:1157:10)
    at Module.load (node:internal/modules/cjs/loader:981:32)
    at Function.Module._load (node:internal/modules/cjs/loader:822:12)
    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:77:12)
[nodemon] app crashed - waiting for file changes before starting...

I can’t find the problem! I am learning so please give a beginner-friendly answer