Unable to access headers from the result of a `fetch`

[digipigeon]

Describe the bug
Unable to access headers from the result of a fetch

To Reproduce
Steps to reproduce the behavior (Run in sandbox):

async function fn () {
  const res = await fetch('https://example.com')

  return res.headers
}

export default await fn()

Expected behavior
We expect to receieve an object (or more specifically a enumerable Headers type) which contains response headers

Desktop (please complete the following information):

• OS: Ubuntu
• Browser N/A
• Version 22.04

[digipigeon]

A quick fix can be to modify the fetch fetch.js adapter from on line 18 from

    headers: res.headers,

to

    headers: Object.fromEntries([...res.headers]),

This will just return an object, but it may be desirable to implement the parent type to allow .get function