[kit v2.68.0] Date are empty object instead of string after form.fields.set(data)

[madmoizo]

Describe the bug

in v2.68.0, after using remote_form.fields.set(data), remote_form.fields.random_date.value() return an empty object instead of a date string.

Reproduction

$effect(() => {
    update_card.fields.set(card);
    console.log(update_card.fields.crafted_at.value());
});

Logs

System Info

System:
    OS: Linux 5.15 Debian GNU/Linux 13 (trixie) 13 (trixie)
    CPU: (16) x64 AMD Ryzen 9 7940HS w/ Radeon 780M Graphics
    Memory: 11.25 GB / 15.23 GB
    Container: Yes
    Shell: 5.2.37 - /bin/bash
  Binaries:
    Node: 26.3.0 - /usr/local/bin/node
    npm: 11.16.0 - /usr/local/bin/npm
  npmPackages:
    @sveltejs/adapter-node: ^5.5.7 => 5.5.7 
    @sveltejs/kit: ^2.68.0 => 2.68.0 
    @sveltejs/vite-plugin-svelte: ^7.1.2 => 7.1.2 
    svelte: ^5.56.4 => 5.56.4 
    vite: ^8.1.0 => 8.1.0

Severity

blocking an upgrade

Additional Information

No response