Getting ReferenceError: app is not defined.

Here is the error details- with source code

[nodemon] restarting due to changes…
[nodemon] starting node server.js

D:eblserverapproutes.js:4
app.get(‘/health’, (_req, res) => {
^

ReferenceError: app is not defined
at Object.<anonymous> (D:eblserverapproutes.js:4:1)
at Module._compile (node:internal/modules/cjs/loader:1241:14)
at Module._extensions..js (node:internal/modules/cjs/loader:1295:10)
at Module.load (node:internal/modules/cjs/loader:1091:32)
at Module._load (node:internal/modules/cjs/loader:938:12)
at Module.require (node:internal/modules/cjs/loader:1115:19)
at require (node:internal/modules/helpers:130:18)
at Object.<anonymous> (D:eblserverappapp.js:8:9)
at Module._compile (node:internal/modules/cjs/loader:1241:14)
at Module._extensions..js (node:internal/modules/cjs/loader:1295:10)

Node.js v20.9.0
[nodemon] app crashed – waiting for file changes before starting…

app.js

//app.js
require('dotenv').config('../.env')
const express = require('express')
const app = express();

app.use(require('./middleware'));
app.use(require('./routes'));
app.use(require('./error'));

module.exports = app;

routes.js

 const router = require('express').Router();

 app.get('/health', (_req, res) => {
 res.status(200).json({ message: 'success' })
 });

 module.exports = router

I chnage the path route ‘/health’ to another name ‘/home’, but error is the same