Svelte 5.1.13: Reassigning store leads to `undefined`

[kyoshino]

Describe the bug

Svelte 5.1.13, probably #14195, introduced a regression in the store API, breaking my Sveltia UI library and Sveltia CMS. I had to downgrade to 5.1.12 to get rid of the error.

After creating a store with writable and reassigning a new store to the variable, the store changes to undefined.

My code

Reproduction

REPL: Svelte 5.1.12 / Svelte 5.1.13

In Svelte 5.1.13, the console says world if you uncomment style = writable('svelte');

An interesting thing is the problem can be reproduced even before the init function is called. You’ll notice that the REPL doesn’t call the function.

Logs

No response

System Info

-

Severity

blocking an upgrade

[paoloricciuti]

Uh it probably needs more check before treating it as state (right now is treating style as state which is wrong

[dummdidumm]

The discrepancy is that the initializer does not treat it as state but the reassignment is

[paoloricciuti]

The discrepancy is that the initializer does not treat it as state but the reassignment is

But it shouldn't be treated as state at all in this case

[kyoshino]

In my case, working around the problem should be easy and the codebase has already been upgraded to Svelte 5, so it’s actually not blocking upgrade but a breaking change 😅

[paoloricciuti]

In my case, working around the problem should be easy and the codebase has already been upgraded to Svelte 5, so it’s actually not blocking upgrade but a breaking change 😅

I mean it's a bug not really a breaking change. Will fix asap 😁

[paoloricciuti]

@dummdidumm I've yet to be able to be at the keyboard but I have the reasonable suspect that we just need to add a check for runes mode.

Because basically in rune mode you would never set the kind to state unless it has a $state init (and in that case it would already be state)