[5.43.9] `$effect.pending()` blocks navigation when passing async `{@const}` data to component

[sillvva]

Describe the bug

Using $effect.pending() and passing async data from {@const} to a component seems to block navigation to a page after the first attempt. Removing $effect.pending() works and passing async data from script block works.

This issue first appears in 5.43.9.

Reproduction

https://stackblitz.com/edit/sveltekit-308957-8ktcalyf-ci62tjdw?file=package.json,src%2Froutes%2F[test]%2F%2Bpage.svelte

Logs

System Info

System:
    OS: macOS 26.1
    CPU: (16) arm64 Apple M4 Max
    Memory: 309.19 MB / 48.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 24.11.0 - /Users/sillvva/.nvm/versions/node/v24.11.0/bin/node
    npm: 11.6.1 - /Users/sillvva/.nvm/versions/node/v24.11.0/bin/npm
    pnpm: 10.21.0 - /Users/sillvva/.nvm/versions/node/v24.11.0/bin/pnpm
    bun: 1.2.20 - /Users/sillvva/.bun/bin/bun
  Browsers:
    Firefox: 144.0
    Safari: 26.1
  npmPackages:
    svelte: 5.43.9 => 5.43.9

Severity

annoyance