Title^

Running around generating the nether caused a crash, happened multiple times.

Minecraft: 1.18.1
Forge: 39.0.75
TerraBlender: 1.1.0.73 | https://www.curseforge.com/minecraft/mc-mods/terrablender/files/3619749
Blueprint: 5.1.1 | https://www.curseforge.com/minecraft/mc-mods/blueprint/files/3645224

Crash-Report: https://gist.github.com/Gbergz/647eb18f2b75db17eb1aa1ae857d655b

I did some testing, and this appears to be a Terrablender issue.

This crash is very similar to a TerraBlender issue that's been open for a while: Glitchfiend/TerraBlender#27
Have you tried removing Blueprint and seeing if the crash no longer occurs?
Blueprint might only be in the crash report stack trace because Blueprint has a modded biome system.