.env

NODE_ENV=production

index.js

const express = require('express')
require('dotenv').config()

const app = express()

const someMiddleWare = (req, res, next) => {
  try {
    next()
  } catch(err) {
    next(err)
  }
}

app.get('/', someMiddleWare, (req, res, next) => {
  try {
    throw Error('badddd!')
  } catch(err) {
    next(err)
  }
})

app.use((err, req, res, next) => {
  res.status(500).send('throw an error')
})

app.listen(5000, () => console.log('listening on port 5000 '))

package.json

{
  "name": "next-err",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "dotenv": "^8.2.0",
    "express": "^4.17.1"
  }
}