I was building an app and had placed it at a subdomain that was called ads.
This caused the wildest error in my sveltekit project and it was something supremely frustrating to find out.
Uncaught (in promise) TypeError: error loading dynamically imported module: https://ads.example.com/_app/immutable/entry/start.123.js
I haven't fully isolated it but I'm guessing that my ad blocker blocks anything that looks like it serves out ads and that is what caused my issue. I wish it had been a bit more obvious about what it was doing rather than just stopping the js file from being loaded.