`signIn` with `RedirectableProviderType` type: `response` is possibly `undefined`

Environment

System:
    OS: Linux 5.17 EndeavourOS
    CPU: (12) x64 AMD Ryzen 5 4600H with Radeon Graphics
    Memory: 5.85 GB / 15.07 GB
    Container: Yes
    Shell: 5.8.1 - /bin/zsh
Binaries:
    Node: 16.14.2 - ~/.nvm/versions/node/v16.14.2/bin/node
    Yarn: 1.22.18 - ~/.nvm/versions/node/v16.14.2/bin/yarn
    npm: 8.7.0 - ~/.nvm/versions/node/v16.14.2/bin/npm
npmPackages:
    next: ^12.1.5 => 12.1.5 
    next-auth: ^4.3.4 => 4.3.4 
    react: ^18.1.0 => 18.1.0 

Reproduction URL

https://codesandbox.io/s/objective-mendel-ixpsco?file=/src/App.tsx

Describe the issue

According to documentation when you supply email or credentials provider to signIn function it returns promise of type SignInResponse but in fact return type of the signIn function is Promise<SignInResponse | undefined>.

This typing results in typescript error Object is possibly 'undefined' if you don't check if response exists beforehand.

How to reproduce

1. Specify signIn type to be RedirectableProviderType
2. Chain then to function call
3. Check for response.error
4. See typescript error

Expected behavior

When specifying signIn type to be one of RedirectableProviderType the return type should be Promise<SignInResponse> and not Promise<SignInResponse | undefined>

Start with the linked CodeSandbox reproduction and the signIn client documentation, then trace the signIn type for RedirectableProviderType. Verify that the response.error access no longer produces an undefined warning and that the return type is Promise as expected.