Connect fails silently if no username is provided but only a password

[AuspeXeu]

Consider the following piece of code.

import Server, { AuthenticateError } from 'aedes';
import * as net from 'net';
import { connect } from 'mqtt';

const mqttServer = new Server({
  authenticate(_, __, password, callback) {
    if (password?.toString() !== 'MY GOOD SECURE PASSWORD') {
      const error: AuthenticateError = { ...new Error('Auth error'), returnCode: 4 };
      callback(error, null);
    } else {
      callback(null, true);
    }
  }
});

net
  .createServer(mqttServer.handle)
  .on('error', (err) => console.error(err))
  .listen(1883, '192.168.0.21', () => {
    console.log(`Aedes server listening on 192.168.0.21:1883`);
    const mqttClient = connect('mqtt://192.168.0.21', {
      // username: 'does-not-matter',
      password: 'MY GOOD SECURE PASSWORD',
      reconnectPeriod: 2 * 1000
    })
  })

In this example, the client will never connect and you will never find out why until you comment the username back in.

[robertsLando]

Would you like to submit a PR to fix this?