stacker.news/pages/login.js

import { providers, getSession } from 'next-auth/client'
import Login from '../components/login'

export async function getServerSideProps ({ req, res, query: { callbackUrl, error = null } }) {
  const session = await getSession({ req })

  if (session && res && callbackUrl) {
    res.writeHead(302, {
      Location: callbackUrl
    })
    res.end()
    return { props: {} }
  }

  return {
    props: {
      providers: await providers({ req, res }),
      callbackUrl,
      error
    }
  }
}

export default Login