Debug: Warn on unsupported properties with Proxy

For debug mode only, it might be nice to add a JS proxy that warns when setting unsupported properties. E.g. with a short-link to new issue template for worker-dom.

Thinking about the easiest way to integrate this. If we go with the separate debugging module fetched at runtime, we'd need one for the worker and one for the main-thread. Maybe another output variant is justified? 🤔