fix: improve types for props when using Client-side component API

[ivanhofer]

fix for sveltejs/language-tools#1578

In theory this is a breaking change. So maybe it needs to wait for version 5 of Svelte.

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[dummdidumm]

Yeah that probably counts as a breaking change - also since #8872 I'm kinda nervous to use never as an explicit descriptor to define "this component does not accept props". null is probably better for this.

[ivanhofer]

Ah, didn't knew about this issue. I updated it to use null instead.

[PuruVJ]

Should be minor, unless its for svelte 5? 😅

[ivanhofer]

Just updated it because it is a breaking change ^^. So it belongs to version 5, right?

[dummdidumm]

That's correct. Marking this as draft so it's not accidentally merged early.

[benmccann]

The types are more restrictive, but you wouldn't have been able to pass something that doesn't conform to these types without the code at least breaking at runtime I think? So maybe it's not really a breaking change?

[dummdidumm]

The new mount function in Svelte 5 has the according typings to make the props field required when there are required props.