fix(next-auth): not redirecting to `/undefined` when signIn method throws an error (#11010)
* Fix NextAuth redirecting to /undefined when signIn method throws an
error
@auth/core `Auth` function can return an internalResponse or a Standard
Response. Internal response has a `redirect` attribute. The problem is
that the logic inside `Auth` method when there is an error is returning
a Standard web Response which doesn't have `redirect` attribute but we
can get redirecting url by using `headers.get('Origin')`.
I think this fix this issue:
https://github.com/nextauthjs/next-auth/issues/11008
* Move action test to tests folder
* Remove test-adapter and add reference to docs
* Defend from undefined responseUrl
* Fix linter
* chore(test): simplify tests
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Co-authored-by: Thang Vu <hi@thvu.dev>