Cheers!
I am the dev of Immersive Lighting. One of my users has reported a server crash while trying to load both your mod and my mod in their environment.

The issue can be found here: WittyWhiscash/Immersive-Lighting#3

The user's crash log can be found here: https://pastebin.com/mVQDtgT3

The user reports using Minecraft version 1.15.2, the latest Fabric Loader (they used Fabric Installer), and mod version 0.3.0-pre-release.

Thanks, I will look at it. It is probably an issue with ButtonWidget, I will move it to client side.

Fixed