[svelte-query] createQueries crashes when several items are removed from the array simultaneously

[Doverstav]

Describe the bug

When using createQueries, changes to the array where two or more items are removed simultaneously causes a crash with the following error:

TypeError: can't delete property '3': proxy deleteProperty handler returned false

 in $effect.pre
 in FilterDrawer.svelte
 in ListPage.svelte
 in index.svelte
 in AnchorDecorator.svelte
 in ScrollDecorator.svelte
 in DecoratorWrapper.svelte
 in RenderFragment.svelte
 in ComposeFragments.svelte
 in Noop.svelte
 in AnchorDecorator.svelte
 in ScrollDecorator.svelte
 in DecoratorWrapper.svelte
 in RenderFragment.svelte
 in ComposeFragments.svelte
 in AnchorDecorator.svelte
 in Router.svelte
 in QueryClientProvider.svelte
 in App.svelte

Your minimal, reproducible example

https://svelte.dev/playground/2b60862d9c564cd1b211738f60e6b729?version=5.55.0

Steps to reproduce

1. Go to the linked example
2. Try adding one or several elements to the array using the buttons, notice that it works
3. Try removing a single element using the button, this also works
4. Then try removing two items using the buttons, the page will now crash. Using slice() or splice() makes no difference. (the console in svelte playground isn't great, you'll have to open the console in the browser to see the error proper)

Expected behavior

I expect useQueries to update its result with fewer queries made, but instead it crashes.

How often does this bug happen?

Every time

Screenshots or Videos

createQueriesCrash.mp4

Platform

• OS: Windows
• Browser: Firefox 148.0.2

Tanstack Query adapter

svelte-query

TanStack Query version

v6.1.10

TypeScript version

v5.9.3

Additional context

No response

[ElBartoo]

Would be nice if someone can have a look please

[Doverstav]

Yes, that would be great! The current workaround we use loses a lot of the power of the tanstack-query cache, which is especially painful when there are lots of small requests being made.

Looks like there's a suggested fix in #10342, hopefully that makes it easier to get a fix merged.