fix: update_branch with (anchor).data possible undefined on ios devices

[matteobattista]

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Playground

pnpm add https://pkg.pr.new/svelte@15851

[paoloricciuti]

I don't think this is not the right fix, data needs to be there during hydration, if it's not there we can't just return without doing anything. This is probably some extension messing with the dom or something similar.

If you do want to work on this we also need a test for it tho.

[matteobattista]

Hi @paoloricciuti,
the PR is related to this issue: #15819 maybe i can refactor with:
if (data === undefined) return;

[paoloricciuti]

Hi @paoloricciuti, the PR is related to this issue: #15819 maybe i can refactor with: if (data === undefined) return;

I'll try to take a look later, no tests are failing because generally the data it's there but I have the feeling that this will break in case there's malformed html...the app might render but the whole hydration mechanism will fail and it will be unresponsive.

[matteobattista]

Hi @paoloricciuti , just to share a possible lead — if it helps:
The issue might be caused by a Cloudflare feature called "Mirage", which injects the following scripts into the HTML during edge processing:

<script type="text/javascript">
//<![CDATA[
window.__mirage2 = {petok: "..."};
//]]>
</script>
<script src="https://ajax.cloudflare.com/cdn-cgi/scripts/04b3eb47/cloudflare-static/mirage2.min.js"></script>

This is not part of the SvelteKit app itself — it’s automatically added by Cloudflare when the Mirage optimization is enabled in the dashboard under Speed > Optimization > Mirage.

So if anyone else is seeing unexpected <script> tags inside HTML elements (like inside a <div>), this could be the reason.

Let me know if this helps clarify things!

[Rich-Harris]

We'd need a test before we could merge this, otherwise it's very likely we'll regress. Can you reproduce the issue?

[matteobattista]

Thank you for considering my post 🙏🏻 ...I understand that making such a change could solve one problem but potentially introduce others.

To reproduce the issue, I believe you can follow what's already described in the other report: #15819.

On my end, I was able to work around it by disabling the option in Cloudflare that was causing it — as shown in the attached screenshot:

Under Speed > Optimization > Image Optimization > Mirage > (off)