react-email should automatically use the next available port

[yeskunall]

Goals

1. Improve DX

Background

Currently, if you simply do email dev (without passing a port explicitly), it crashes with an ugly stack trace:

- error Failed to start server
Error: listen EADDRINUSE: address already in use :::3000
    at Server.setupListenHandle [as _listen2] (node:net:1817:16)
    at listenInCluster (node:net:1865:12)
    at Server.listen (node:net:1953:7)

...rest of the frames skipped

While you can pass -p <port> to use a different port, I think it would greatly improve DX if react-email automatically found the next available port when 3000 is already taken (as is the case if you’re using Next.js as-is AKA without passing PORT to it)

Proposal

Many dev commands already support this, and I’m sure there’s many ways to do this, but off the top of my head:

Use get-port, and pass it a list of default ports to use, and if all of them happen to be taken, assign a random port.

Again, I’m sure this can be achieved in many ways, so if my proposed solution does not fit well with you guys, feel free to suggest an alternative.

Are you interested in contributing?

Sure, I can try.