[fix] support and pin undici 5.12.0

[repsac-by]

Fixes #7409

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🦋 Changeset detected

Latest commit: 7873c25

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

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@sveltejs/kit	Patch

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[jalavosus]

Not to knock your fix (it's a good one) but wouldn't a more stable fix be to pin to the last known good version of undici (5.11.0)?

[repsac-by]

There are many fixes and improvements in 5.12.0.
I don't see any good reason to stay with 5.11.0 other than the addition of the duplex property.

[N00nDay]

Worked like a charm for me. Thanks repsac-by

[benmccann]

The Undici team indicated this is the correct fix

This is part of the spec now. When you have a ReadableStream body, the duplex option is required.

[benmccann]

I would expect we shouldn't need this. Is there some detail we can add here about how/when we might be able to remove it. Are the types provided by Typescript or Undici? Is there and open issue we can link to or can we file a new one?

[Conduitry]

These types appear to be coming from TS, not from undici. Locally, even when I updated the Kit repo to undici 5.12.0, TS still complained about the duplex.

[Conduitry]

The undici PR included updates to the types here (https://github.com/nodejs/undici/pull/1681/files#diff-cfe294cd3fb885afcce564fae32dd1524399460a9a04f141e07bb45858a47f92), but it looks like we're not using those. I tries this out locally (and updated the Kit repo to undici 5.12.0), but the types for Request appeared to be coming from TypeScript (lib.dom.d.ts) and not from undici. This @ts-expect-error is probably the best we can do for now. Once the types are added to TS and we upgrade, we'll start getting an error here, so at least we'll remember to remove this.

This change looks good to me. Can we get a changeset?

[benmccann]

We should probably pin the Undici version as well as they've indicated that it's experimental and may have breaking changes in minor/patch versions: nodejs/undici#1681 (comment)

[Conduitry]

That sounds good to me as well.