The server listening on an undefined port

Make the service start locally and in production when PORT is optional.

10 min/Node.js / environment variables / safe defaults

Observe

Investigate

Fix

Verify

Reflect

server.js/javascript

01020304050607

import http from "node:http";

const PORT = process.env.APP_PORT;

http.createServer((_request, response) => {
  response.end("ok");
}).listen(PORT);

Terminal0 runs

RangeError [ERR_SOCKET_BAD_PORT]: options.port should be >= 0 and < 65536.
Received undefined.

npm ERR! code ELIFECYCLE
npm ERR! command failed