How to catch fetcher thrown errors?

[ioucyf]

I'm working with supabase, and I find myself more often wanting to handle the errors thrown by fetcher on the client when for example supabase fails to refresh a token (to update the supabase's auth state on the client).

I tried adding event listeners to window as such in routes/+layout.svelte:

<svelte:window
	on:error={errorEventHandler}
	on:unhandledrejection={errorEventHandler}
	on:rejectionhandled={errorEventHandler}
	on:messageerror={errorEventHandler}
/>

and I also tried adding the same listeners in hooks.client.ts which results in duplicating, as expected, the same effects as the one I setup on window in routes/+layout.svelte
Yet none of which seem to 'listen' for it. I do catch other events through the listeners, but never fetcher's errors.

Any ideas?