I'm using Preact following the "no build tools" route in the Getting Started guide. (It's a great option for these tiny demos I'm working with!)

This import statement finds something to load:

import "https://unpkg.com/preact@latest/debug/dist/debug.module.js?module";

then it dies because process is undefined.

Adding this to my document before I load my module makes it work. I think. Preact Developer Tools does connect and recognize the component.

<script>
  window.process = {env: {NODE_ENV: 'development'}};
</script>

but there's some room for improvement there. Probably both in the preact/debug module build so it doesn't rely on the nodejs environment, and in the debugging guide.