While trying to build user authentification using mongodb and express I came across an error. The error basically happens every time I click submit on the website. That's the first problem, the second is after I click submit the page just keeps loading and never changes as if its stuck or trapped in an infinite loop. I tried deleting everything in the database and starting over but that didn't work. A little advice would be appreciated.

The error:

app: authRouter {
  app: authRouter   acknowledged: true,
  app: authRouter   insertedId: new ObjectId("613b5afd2139aeac87bd9682")
  app: authRouter } +0ms
  app: authRouter TypeError: Cannot read property '0' of undefined
  app: authRouter     at addUser (C:\Users\Yanki XXIV\Desktop\pluralsight\src\routers\authRouter.js:24:30)
  app: authRouter     at processTicksAndRejections (internal/process/task_queues.js:95:5) +19ms

authRouter.js:

const express = require('express');
const debug = require('debug')('app: authRouter');
const { MongoClient } = require('mongodb');

const authRouter = express.Router();

authRouter.route('/signUp').post((req, res) => {
  const {username, password} = req.body;
  const url = 
  'mongodb+srv://Yoshi:Yumcmaster1@cluster0.atic5.mongodb.net?retryWrites=true&w=majority'
  const dbName = 'testdb';

  (async function addUser(){
      let client
      try {
        
        let client = await MongoClient.connect(url);
          
        const db = client.db(dbName);
        const user = {username, password};
        const results = await db.collection('users').insertOne(user);
        debug(results);

        req.login(results.ops[0], ()=> {
          res.redirect('/auth/profile');
        });
        



      } catch (error) {
        debug(error)
      }
      client.close();
  }());

});
authRouter.route('/profile').get((req, res) => {
    res.json(req.user);
})

module.exports = authRouter;