Write after end error when launch server in nodejs

I am beginner at NodeJS and Im doing a “NodeJS and Express.js full course” at freecodecamp yt and I copied author code wich for him works perfectly but I got an error.

Code:

  const server = http.createServer((req, res)=> {
if(req.url === '/') {
  res.end('Home Page')
}
if(req.url === '/about') {
 res.end('About us')
}
res.end('Error')
})

server.listen(3000, ()=>{
  console.log('Server listening...');
})

Idk why He got home, about and error page when user go to wrong page it should throw “Error” text on page, but instead my program is throwing an error in nodeJS program:

events.js:377
    throw er; // Unhandled 'error' event
     ^

Error [ERR_STREAM_WRITE_AFTER_END]: write after end
    at new NodeError (internal/errors.js:322:7)
    at writeAfterEnd (_http_outgoing.js:694:15)
    at ServerResponse.end (_http_outgoing.js:815:7)
    at Server.<anonymous> (C:UsersjonatDesktopnodejsapp.js:10:5)
    at Server.emit (events.js:400:28)
    at parserOnIncoming (_http_server.js:900:12)
    at HTTPParser.parserOnHeadersComplete (_http_common.js:127:17)
Emitted 'error' event on ServerResponse instance at:
    at writeAfterEndNT (_http_outgoing.js:753:7) 
  at processTicksAndRejections (internal/process/task_queues.js:83:21) {
  code: 'ERR_STREAM_WRITE_AFTER_END'
}

Can someone explain this to me? I would be appreciate. Thank you in advance.