Lots of good suggestions. However for Svelte in particular I’ve had a lot of trouble. You can get good results as long as you don’t care about runes and Svelte 5. It’s too new, and there’s too much good Svelte code out there used in training that doesn’t use Svelte 5. If you want AI generated Svelte code, restricting yourself to <5 is going to improve your results.

(YMMV: this was my experience as of three or four months ago)