"cookies is not iterable" error thrown when trying to iterate over a fetch response that contains a Set-Cookie header

[dtinth]

Version

18.14.1

Platform

Darwin dtinth-m1.local 22.1.0 Darwin Kernel Version 22.1.0: Sun Oct 9 20:14:30 PDT 2022; root:xnu-8792.41.9~2/RELEASE_ARM64_T8103 arm64

Subsystem

undici

What steps will reproduce the bug?

See: nodejs/undici#1935

How often does it reproduce? Is there a required condition?

See: nodejs/undici#1935
See: sveltejs/kit#9091

What is the expected behavior?

No error

What do you see instead?

 error   cookies is not iterable
  File:
    /Users/dtinth/Projects/contentsgarten/creatorsgarten/src/pages/api/contentsgarten/[action].ts:82:47
  Code:
    81 |     const response = await fetch(backendUrl, {
    > 82 |       method: request.method,
         |                                               ^
      83 |       headers,
      84 |       body: request.body,
      85 |     })
  Stacktrace:
TypeError: cookies is not iterable
    at get [headers map sorted] (node:internal/deps/undici/undici:1844:34)
    at node:internal/deps/undici/undici:1865:43
    at Headers Iterator.next (node:internal/deps/undici/undici:1108:26)
    at Function.from (<anonymous>)

Additional information

The issue nodejs/undici#1935 is already closed because there was a merged PR that fixes the issue nodejs/undici#1936

However, a Node.js version with the fix has not been released yet… So the issue is shifted to Node.js side to release a version of undici with the fix (or rollback the version of undici that adds the regression).

[mcollina]

Thanks for reporting. A fix is incoming.