Unexpected Components Behavior in SvelteKit with Turborepo

[pepa-linha]

Hi!

I'm working on a SvelteKit project set up with Turborepo. My components are located in app/web/src/lib/components, but the problem arises when I move a component to the ui package (packages/ui).

Components in the ui package don't compile, and they are imported directly, for example:

import MyComponent from "@myrepo/ui/components/MyComponent.svelte";

The import works fine, but the same component behaves differently depending on whether it's placed in app/web or packages/ui, and I can't figure out why.

Issues I've discovered:

• The passed props aren't equally reactive.
• When toggling a class with class:foo, it doesn't always get removed correctly when foo is false.

However, if I import the component (same code) directly from app/web:

import MyComponent from "$lib/components/MyComponent.svelte";

these issues do not occur, and everything works fine.

Has anyone encountered similar issues?

Thank you very much!

[pepa-linha]

So I found a problem that I couldn't easily simulate before.

The problem is related to TypeScript, <script lang="ts"> and ...rest parameter when using svelte-preprocess.

My solution was to get rid of the dependency https://www.npmjs.com/package/svelte-preprocess (which I was using for historical reasons) and use the classic vite preprocess.

There is also an old issue on github: sveltejs/svelte-preprocess#662