To Reproduce
Simply interrupt the play of a song from the Transmitter; either by pressing the stop button or by switching to another song

Crash Logs
Server crash log

Environment (please complete the following information):

• OS: check the crash log; idk my host's exact OS details
• Mod Version: 4.0.0
• Minecraft Version: 1.19.2
• Forge Version: 43.2.14

Additional context
I will try and see if I can narrow it down to what caused this. I was mainly just playing around with the new/changed features on a server that previously used older versions of MIMI. It could also very well be the plethora of mods I have that caused this, in which case I'd be happy to help assist you in finding which mod is causing it.

Thank you so much for the bug report! I'm looking into that right now

I've just uploaded the release builds for 4.0.0 which should fix this issue but let me know if you continue to have problems!