I'm working on a SvelteKit project that streams a big array of items in chunks to the browser using an AsyncGenerator. I'm trying to make this array in such a way so that it:

1. Can be SSR'd.
2. Is reactive so as more data streams in the UI updates.

Here is part of the core of my setup:
https://svelte.dev/playground/867fe279c37946d2818245b76ebb8812?version=5.34.3
Updating thestart number causes the numbers array to recalculate (Imagine that thestart parameter is page data from a SvelteKit load function, and the sleep calls are the array waiting for the next piece from the server side AsyncGenerator).

I've had success by putting$state inside a$derived.by ages ago, but it seems some recent updates have broken that for me. I started gettingstate_unsafe_mutation errors.

Turns out by wrapping the state update inuntrack helps, though I don't completely understand why. It seems something to do with this discussion?https://svelte.dev/playground/867fe279c37946d2818245b76ebb8812?version=5.34.3

After poking around on the docs foruntrack andstate_unsafe_mutation I noticed that the latter says "If side effects are unavoidable, use and$effect instead":https://svelte.dev/docs/svelte/runtime-errors#Client-errors-state_unsafe_mutation

Is what I'm trying to do here considered a "side effect"? Should I be using an$effect to update my array instead of trying to use$derived.by?