Svelte 5 is breaking sites (including the Svelte 5 preview site)

[Ocean-OS]

Describe the bug

When going to the svelte 5 preview site, it flickers and then shows nothing other than a gray screen. When checking devtools, it has this error:

It also appears to affect other Svelte 5 sites, as shown by @itsneeku.

Reproduction

Go to the Svelte 5 preview site.

Logs

class.CTOAjPUp.js:1 
 Uncaught (in promise) TypeError: Cannot set property width of #<SVGSVGElement> which has only a getter
    at z (class.CTOAjPUp.js:1:3883)
    at focus-outside.BZqWhF3q.js:1:1248
    at Mt (runtime.CZX3LrFh.js:1:7787)
    at j (runtime.CZX3LrFh.js:1:8567)
    at b (runtime.CZX3LrFh.js:1:3689)
    at z (runtime.CZX3LrFh.js:1:4567)
    at Ir (runtime.CZX3LrFh.js:1:4599)
    at N (focus-outside.BZqWhF3q.js:1:1241)
    at external-links (0.CRbYljr2.js:1:31135)
    at q (theme.Ci2GTQxT.js:1:150)

System Info

Tested on Chromium (latest) and Microsoft Edge (latest).

Severity

blocking all usage of svelte

[itsneeku]

Its affecting static builds deployed on gh pages as well: https://neeku.dev/concordia-ics-builder/

[o-az]

I’m using this deployment from 30 days ago until current svelte 5 docs are fixed

https://svelte-5-preview-iu6hmd250-svelte.vercel.app/docs/introduction

[Conduitry]

More broadly: #13327 doesn't appear to account for cases where the DOM property exists but is read-only.

[Ocean-OS]

More broadly: #13327 doesn't appear to account for cases where the DOM property exists but is read-only.

After looking through the built code I'm pretty sure the function causing the error is here.

[Conduitry]

This has been fixed in #13341.