Websocket API question

Volumio Information

Volumio Version: v2.861
Hardware: Raspberry Pi
DAC: Hifiberry DAC+

I’m trying to connect the Websocket API from nodejs.
I have code working using the socket.io-client@2.4.0, but the same code fails using the latest socket-io-client@3.1.0 with an error Error: server error, code: 'parser error' and I cannot find what’s wrong with my code.

const io = require('socket.io-client');
const socket = io('');
socket.on('connect_error', err => { 
  console.log('Connect error to volumio', err);
socket.on('connect', () => { 
  console.log('Connected to volumio');
socket.on('pushState', data => { 
  console.log('pushState', data);

Can you provide any help for getting this running with socket.io-client@3.1.0?