Why Morgan Logger server middleware doesn't work in separate file?

I am following this tutorial in my nextjs app for adding a new middleware for logging so I have the following code in my server.js:

// create a write stream (in append mode)
const accessLogStream = fs.createWriteStream(path.join(__dirname, 'access.log'), { flags: 'a' })

// setup the logger
server.use(morgan('combined', { stream: accessLogStream }))

And it is working without a problem.

But I want to have the logic in a separate file in the middleware directory so I have :

middlewares/logger/index.js

import morgan from "morgan";
import fs from 'fs';
import path from 'path';


export default (req, res, next) => {
  var accessLogStream = fs.createWriteStream(path.join(__dirname, 'access.log'), { flags: 'a' })

  return morgan('combined', { stream: accessLogStream });
};

and in my server.js I will have: (after importing and initializing stuff)

  server.use(logger);
  server.use(othermiddlewareone);
  server.use(othermiddlewaretwo);

The other middlewares are working fine but this one breaks. Do you know why is that?

I changed the middleware like this and now it is working fine :)

import type { Request, Response, Next } from './types';
import morgan from "morgan";
import fs from 'fs';
import path from 'path';

const accessLogStream = fs.createWriteStream(path.join(__dirname, 'server.log'), { flags: 'a' })
const logger = morgan('combined', { stream: accessLogStream })

export default async (req: Request, res: Response, next: Next) => {
  logger(req, res, function (err) {
    return next();
  })
};