Error message "Batch has scheduled roots"

Why this is a good first issue

Internal Svelte error with unclear reproduction steps.

AI Summary

The issue involves an internal Svelte error ('Batch has scheduled roots') triggered when using a derived value in an {#each} loop. The maintainer has requested a reproducible example, which is currently missing. The error suggests a flaw in Svelte's internal assumptions, but without a clear reproduction, it's difficult to diagnose or fix.

Issue Description

Describe the bug

Hello, after upgrading to the latest version I get this error message when I try to render an {#each} loop where the array comes from a derived.by.

Reproduction

I was able to create a minimal reproduction by stripping down my project step by step.

The resulting repository can be found here: https://github.com/JoBurgard/svelte-repro-batch-has-scheduled-roots/

Logs

Uncaught Svelte error: invariant_violation
An invariant violation occurred, meaning Svelte's internal assumptions were flawed. This is a bug in Svelte, not your app — please open an issue at https://github.com/sveltejs/svelte, citing the following message: "Batch has scheduled roots"
https://svelte.dev/e/invariant_violation

  in <unknown>
  in undefined
  in undefined
    invariant_violation http://localhost:3000/public/dist/bundle/extractor-view.js:129
    invariant http://localhost:3000/public/dist/bundle/extractor-view.js:677
    #commit http://localhost:3000/public/dist/bundle/extractor-view.js:1160
    #process http://localhost:3000/public/dist/bundle/extractor-view.js:1053
    flush http://localhost:3000/public/dist/bundle/extractor-view.js:1118
    ensure http://localhost:3000/public/dist/bundle/extractor-view.js:1225
    run_all http://localhost:3000/public/dist/bundle/extractor-view.js:59
    run_micro_tasks http://localhost:3000/public/dist/bundle/extractor-view.js:787
    flush_tasks http://localhost:3000/public/dist/bundle/extractor-view.js:801
    flushSync http://localhost:3000/public/dist/bundle/extractor-view.js:1287
    set value http://localhost:3000/public/dist/bundle/extractor-view.js:6414
    set http://localhost:3000/public/dist/bundle/extractor-view.js:5679
    set http://localhost:3000/public/dist/bundle/extractor-view.js:5905
    set_attributes http://localhost:3000/public/dist/bundle/extractor-view.js:5226
    attribute_effect http://localhost:3000/public/dist/bundle/extractor-view.js:5247
    update_reaction http://localhost:3000/publi