Svelte 5: Setting a store tries to update the signal instead in certain situations

[Conduitry]

Describe the bug

In a SvelteKit app, I'm putting a store on data so that one page can tell a layout about whether to temporarily hide a navigational item. Svelte 5's $: sorting logic appears to differ from Svelte 4's in this case, and the update to the store is trying to happen before the store itself has been destructured from the data prop. (At least that's what I think is happening. I'm still not sure though why I'm getting 'store.set is not a function' and not 'store is not defined' if this is the case.)

In my case, the workaround is pretty easy - use store.set(...) instead of $store = ... - but it was still confusing, especially when this was being masked by #12857.

Reproduction

https://svelte-5-preview.vercel.app/#H4sIAAAAAAAACo2PzW7DIBCEXwWhSLGlKNypbalvkHvTA7GXChUDgnV_hHj3AnbcSu2hx935ZncmUqk0BMqfIjViBsrpo3P0RPHTlSG8gUbIc7CLH8umC6NXDoeruaKanfVIInn3CsVNA0lEejuT4-pjAa2H48MP9iJeYGPOrAznFa1QxkZrApLqI_1-t2mz3LHv16arhyaBoo9x41NiWcthZzspqWCiHP0C6bR3K6b_loOPGlgD1je1xIGTZv-W8xWhrUrBpLV5J4UOcKcP9yZZ-1XhtiBaQ6zho1bjax-blvTDdqYmH6rQsZXMrrgeTH_VfE5fZEDWkM4BAAA=

Logs

No response

System Info

n/a

Severity

annoyance

[Conduitry]

It's possible it's not a sorting thing at all, but some other issue. Here's another simpler reproduction that also has the 'store.set is not a function' error, this time upon clicking the button.

https://svelte-5-preview.vercel.app/#H4sIAAAAAAAACo2PwU7DMBBEf2VlVWoqVc3dJJH4A-60B9fZIAvHtuwNFFn-d2ynBCQ4cNydN7szkU1KY2D8OTIjZmScPTrHjow-XBnCG2rCPAe7eFk2XZBeORrO5kxqdtYTRHj3isRVIySYvJ1hv_raQNbj_uEH-yRe8M6c2jKcVrRCGZPWBILqg36720xCBzxkpmu__5uuXhsFiT7GuymlNms58WxHNSkcGSe_YDpuBYvpvw3xVlNrpPqmNtlxaLZvOWQRfke7LkTWgDVcaiVf-9gcoB9g91Wthhqq1rUrnI1x1dNfDS7pE8lzaU2uAQAA

[Conduitry]

Yeah, I think the issue is that $.store_set() is getting passed the signal rather than the store object. I've updated the issue title, but left the old OP for now.

Presumably either $.store_set(store, true); should be $.store_set($.get(store), true);, or else $.store_set should be able to accommodate being passed a signal.

[trueadm]

Was this working for you in a previous version?

[Conduitry]

I believe so, yes. Let me try to figure out when.

[Conduitry]

It looks like it broke between 213 and 214. That sounds like #12780 then, but that's a pretty big one.

[Conduitry]

👍 This looks good now in my original app in 232.