sos-nextjs/pages/_error.js

import React from 'react'
import getConfig from 'next/config'

const {publicRuntimeConfig} = getConfig()

const ErrorPage = ({error}) => {
  const env = publicRuntimeConfig.SOS_ENV
  if (!error)
    return (
      <>
        <h2>Not Found</h2>
        <p>We couldn't find the item you're looking for.  Sorry!</p>
      </>
    )

  return (
    <>
      <h2>{error.name}</h2>
      <p>{error.message}</p>
    </>
  )
}

ErrorPage.getInitialProps = ({ctx: {err, req, res}}) => {
  if(!err) return {error: null}

  if(res)
    err.status = res.statusCode

  return { error: err }
}

export default ErrorPage