Inexistant hash in URL throws during load finalization

[WarningImHack3r]

Describe the bug

kit/packages/kit/src/runtime/client/client.js

Line 2804 in 5594597

if (!app.hash && location.hash && document.querySelector(location.hash)) {

The call to document.querySelector on this line throws when the hash is not found on the page. This is a regression introduced in 2.21.3 by #10856.

Reproduction

Visit any website with 2.21.3+, append an incorrect hash at the end of the URL, and refresh

Logs

Uncaught (in promise) SyntaxError: Failed to execute 'querySelector' on 'Document': '#somehash' is not a valid selector.
    at reset_focus (client.js?v=3f49ea1a:2804:46)
    at navigate (client.js?v=3f49ea1a:1630:3)
    at async HTMLHtmlElement.<anonymous> (client.js?v=3f49ea1a:2381:3)

System Info

System:
    OS: macOS 15.5
    CPU: (10) arm64 Apple M1 Pro
    Memory: 155.81 MB / 16.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 24.2.0 - /opt/homebrew/bin/node
    npm: 11.4.1 - /opt/homebrew/bin/npm
    pnpm: 10.12.1 - /opt/homebrew/bin/pnpm
    bun: 1.2.15 - ~/.bun/bin/bun
  Browsers:
    Chrome: 137.0.7151.104
    Safari: 18.5
    Safari Technology Preview: 18.4
  npmPackages:
    @sveltejs/adapter-vercel: ^5.7.2 => 5.7.2 
    @sveltejs/kit: ^2.21.4 => 2.21.4 
    @sveltejs/vite-plugin-svelte: ^5.1.0 => 5.1.0 
    svelte: ^5.33.19 => 5.33.19 
    vite: ^6.3.5 => 6.3.5

Severity

serious, but I can work around it

Additional Information

As try-catching the call to querySelector is likely the easy fix, I'd love if you could make it so that the hash "DOM search" is run once again when the page is fully ready if the hash is not instantly found where this snippet is currently called.

{#await Promise.resolve() then _}
    <span id="myhash">This text being rendered is what I consider a "ready" page</span>
{/await}