URQL not compatible with new SvelteKit fetch polyfill

[Nickersoft]

Hey folks, from my understanding, SvelteKit has recently adopted node-fetch to use as a fetch polyfill, and with it seems to be breaking SSR rendering attempts using SvelteKit with URQL. Attempting to use the fetch polyfill in the URQL from the server now results in:

Error: [Network] Request with GET/HEAD method cannot have body.

An example of an offending load function can be found here.

urql version & exchanges:

@urql/core: 2.5.0
@urql/exchange-graphcache: 4.4.3
@urql/svelte: 2.0.2

Steps to reproduce

I've updated my urql-example repo from the last time I posted here to highlight the issue. Just run yarn dev and the issue should happen on page load.

Expected behavior

The fetch call should function the same as it would in the browser. I'm not 100% this is entirely a URQL repo, as I did some digging and saw some unexpected logic happening inside node-fetch, but seeing this is where I saw the issue first, I figured I'd rule it out with you guys before opening any other issues.

Actual behavior

Described above.

[JoviDeCroock]

I mean, this sounds like a Svelte issue we are explicitly using POST as long as you don't activate useGETMethod https://github.com/FormidableLabs/urql/blob/main/packages/core/src/internal/fetchOptions.ts#L88

[Nickersoft]

Hmm... that's what I thought. And you're right, this does look like an upstream issue: sveltejs/kit#5383 (posted 5 hours ago). Closing to follow the progress over there! Thanks for confirming.