Webhook stops working with no obvious reason

I followed the webhook tutorial Using webhooks and installed a custom app listening on my site’s page update events.

Sometimes the app stops working altogether after a while. No page change event get picking up. Any suggestion where to look what might have gone wrong?

This is ‘NPM start’ on windows with nearly no change from the original code, it is in Node.js.

Also any suggestion if I can provide an endpoint to listen to these update events without using Node.js?

Thanks in advance