• Mod version: chisel-neoforge-1.21.1-1.8.2
• Minecraft version: 1.21.1
• NeoForge version: 21.1.115
• No other mods installed.

Error:

[main/ERROR] [net.neoforged.fml.common.asm.RuntimeDistCleaner/DISTXFORM]: Attempted to load class net/minecraft/client/gui/screens/inventory/AbstractContainerScreen for invalid dist DEDICATED_SERVER

Anyway, server is stated.

Full log: https://gist.github.com/MultiMote/4bc60dcb6bdd266eeff521375e8fabab

Tested on latest commit, could not reproduce.

Still can reproduce with last commit (bff9f78).

Command: gradlew -p neoforge runServer

latest.log

what environment are you running this from?

Windows 10
OpenJDK Runtime Environment Temurin-21.0.5+11 (build 21.0.5+11-LTS

I think you forgot to annotate gui class with

@OnlyIn(Dist.CLIENT)

or something related to this.