Starting a second instance on the same host doesn't throw an error or exit

[voipmeister]

Describe the Bug Not quite a bug (but no feature either I think), but while checking different versions of Node and Enigma I accidentally started a second instance. The second instance wasn't bound to port 8888/tcp ofcourse, but there was no warning message either. Would be nice to have a warning message and exit IMHO.

To Reproduce Any relevant steps to reproduce the behavior: Deploy a second installation of Enigma on the same host; start the first instance and the start the second instance.

Desired Behavior Would be nice to have a warning message and exit IMHO.

Actual Behavior The second instance isn't bound to port 8888/tcp and there's no warning message either.

Environment

• [x] I am using Node.js v14.x LTS or higher
• [x] npm install or yarn reports success
• Actual Node.js version (node --version): v18.20.4
• Operating system (uname -a on *nix systems): Linux bbs01 6.1.21-v8+ #1642 SMP PREEMPT Mon Apr 3 17:24:16 BST 2023 aarch64 GNU/Linux (Raspberry Pi 3B)
• Revision (git rev-parse --short HEAD): 9c0bc88f
• Any additional relevant information about your setup: None, I think :)