Why fetch wrappers require src/hooks.server.js ?

[KaKi87]

Hello,

When wrapping SvelteKit load's fetch with ofetch or itty-fetcher, the following error appears :

Error: Failed to get response header "content-type" — it must be included by the filterSerializedResponseHeaders option: https://kit.svelte.dev/docs/hooks#server-hooks-handle

At first I thought the issue was caused by the latter, but then I also tried with the former and still was experiencing it, making it a Svelte issue.

And, when I tried the suggested fix :

/** @type {import('@sveltejs/kit').Handle} */
export const handle = ({
    event,
    resolve
}) => resolve(
    event,
    {
        filterSerializedResponseHeaders: name => name === 'content-type'
    }
);

It works. But why ? From my point of view, I might as well prepend // Magic, do not touch 😅

Thanks

[terwer]

I have the same question too.