Hovering a link that leads to a page with a remote function freezes the page

[mikolajkazmierczak]

Describe the bug

I found that when I hover over a link that leads to page where I use a remote function the whole page freezes. I have to close the browser tab and open a new one. It doesn't happen everytime though. Sometimes I have to navigate back and forth for it to happen.

I also found that if I apply data-sveltekit-preload-data="off" to the link then everything works fine. I do have some redirects in my load function, don't know if this related to this issue.

Reproduction

as described above, reproduction proves difficult

Logs

System Info

svelte 5.46.0
sveltekit 2.49.2

Severity

serious, but I can work around it

Additional Information

No response

[soniquete0]

I encountered this issue myself yesterday in my own project (kit 2.48.5, svelte 5.43.12). It's not necessarily caused by remote function but by the async experimental feature.
I made a minimal repro (kit 2.49.1, svelte 5.45.6) - https://github.com/soniquete0/svelte-async-bug-repro
The only way I was able to reliably reproduce this was with bits-ui.

1. Run the repro
2. Navigate from / to /test by clicking the "Go to test page" link
3. Check the "bits-ui Checkbox":
   • bits-ui checkbox won't change icon
   • rendered state changes value
   • native checkbox works
   • inspect in console shows state changes value
4. Refresh the page
5. Check the "bits-ui Checkbox":
   • bits-ui checkbox does change icon
   • rendered state changes value
   • native checkbox works
   • inspect in console shows state changes value
6. Hover link "Back to home" at the bottom
7. Check the "bits-ui Checkbox":
   • bits-ui checkbox won't change icon
   • rendered state won't change value
   • native checkbox works but the rendered state value won't change anyway
   • inspect in console shows state changes value

I believe these two are two separate, yet related issues.
The navigation bug can be "fixed" by calling the remote function without await and items.current?.items instead of items.items
The hover bug can be "fixed" by moving the +page.server.ts code from homepage to remote function (or by commenting it out/removing the code in +page.server.ts).
Both bugs can be fixed by removing the experimental async function and calling the remote function without await.

I suspect this issue might be related - #15058 and sveltejs/svelte#17309 and sveltejs/svelte#17197

This PR sveltejs/svelte#17335 seems to fix the hovering a link issue but not the navigation issue

[harishkswamy]

Looks like a similar issue that I am facing but I have a simple two route app that reproduces the issue