Base information

• Minecraft version: 1.16.5
• Mod version: 3.0.20.440
• Minecraft Forge version: 36.2.20
• Mod Pack: custom

Crash report

(crash-report)

Description / steps to reproduce

I don't know wether it is reproducable, it seemed pretty random to me and only happened once. The second, I placed the energy core block, the entire server crashed. Upon restart, it crashed again with the same error message, but after a few tries of re-restarting, it somehow fixed itself again.

Looks like a very edge case issue but regardless it should be fixed in the next update.
Also it wouldn't have made a difference in this case but in future please make sure your running the latest version before reporting bugs.