NodeJS Net server crashes upon nmap scan

I have programmed a server based on the Net module of NodeJS. It works perfectly fine, if I try to connect to it using a Net socket. However, if I try to scan it with nmap, it can't write to the socket, giving an EPIPE error.

    Error: write EPIPE
    at afterWriteDispatched (node:internal/stream_base_commons:160:15)
    at writeGeneric (node:internal/stream_base_commons:151:3)
    at Socket._writeGeneric (node:net:775:11)
    at Socket._write (node:net:787:8)
    at writeOrBuffer (node:internal/streams/writable:400:12)
    at _write (node:internal/streams/writable:341:10)
    at Socket.Writable.write (node:internal/streams/writable:345:10)
    at Server.<anonymous> (/server.js:6:10)
    at Server.emit (node:events:379:20)
    at TCP.onconnection (node:net:1555:8)
Emitted 'error' event on Socket instance at:
    at emitErrorNT (node:internal/streams/destroy:188:8)
    at emitErrorCloseNT (node:internal/streams/destroy:153:3)
    at processTicksAndRejections (node:internal/process/task_queues:81:21) {
  errno: -32,
  code: 'EPIPE',
  syscall: 'write'
}

I have simplified the server code to this:

const net = require('net');
const server = net.createServer(socket => {
  socket.write('Test');
});
server.listen(30);

The nmap output just sais 30/tcp open tcpwrapped. I'm sure it has something to do with how nmap connects to the server. But I just can't work out how.