Version Info

• Minecraft, ... 1.21.1
• Rechiseled, ... 1.1.6
• Fusion, ...

What mod loader are you using?: Fabric/Forge/NeoForge/Quilt
Forge
Steps to Reproduce
...

Crash report (~/logs/latest.log)
...Error: java.lang.NullPointerException: Cannot invoke "java.util.List.iterator()" because "com.supermartijn642.rechiseled.chiseling.ChiselingRecipes.chiselingRecipes" is null

This has been fixed now in Forge 52.0.29.
Thank you for reporting the issue!

This is caused by I by a mistake in Forge, one that I actually introduced in a pull request I submitted 🙃
I have submitted another PR to fix my previous mistake here MinecraftForge/MinecraftForge#10171.
The issue should go away once that is merged.