fix(ts): improve unstable_getServerSession return type

[balazsorban44]

Currently, unstable_getServerSession assumes that it always returns a Session. However, in practice, it should match the session callback's return type. This can be used to create feature parity with getToken like this:

// app/page.tsx
import { getToken } from "next-auth/jwt"
import { unstable_getServerSession } from "next-auth/next"
import { headers, cookies } from "next/headers"

export default async function Page() {
  const session = await unstable_getServerSession({
    callbacks: { session: ({ token }) => token },
  }) // session will take the shape of JWT

  const token = await getToken({
    req: {
      headers: Object.fromEntries(headers()),
      cookies: Object.fromEntries(cookies().getAll().map((c) => [c.name, c.value])),
    } as any,
  })

  // These two should look equal
  return (
    <>
      <pre>{JSON.stringify(session, null, 2)}</pre>
      <pre>{JSON.stringify(token, null, 2)}</pre>
    </>
  )
}

This is an alternative to #5791, reducing the number of APIs needed in the future (no need for getToken). (See #5791 (comment))

Closes #5791, fixes #5754

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1 Ignored Deployment

Name	Status	Preview	Updated
next-auth	⬜️ Ignored (Inspect)		Nov 24, 2022 at 1:42PM (UTC)

[github-actions]

🎉 Experimental release published 📦️ on npm!

pnpm add next-auth@0.0.0-pr.5792.9119ea67

yarn add next-auth@0.0.0-pr.5792.9119ea67

npm i next-auth@0.0.0-pr.5792.9119ea67

[ThangHuuVu]

I really like this approach, save us from exposing another API! 👍 Added 2 comments

[ammmze]

Is it intentional that we are modifying args[2] here? I recently updated next-auth and started getting some odd behavior where I've got places in my app using my authOptions object and it's fine at first, but eventually the providers got cleared out...this is the reason for that.

I suspect we meant to do options = Object.assign({}, args[2], { providers: [] }) instead? Or IMO use the spread operator options = { ...args[2], providers: [] }

[ammmze]

I've opened a PR that should fix this.