Minecraft v1.12.2
Forge v14.23.5.2838
Charset Storage - Barrels v0.5.5.7
Charset Storage - Lib v0.5.5.7
Biomes You'll Go v1.6.7
JEI v4.15.0.285

I got this crash after typing bamboo into the JEI search bar. This seems to have happened after adding BYG's Bamboo Log byg:bamboolog and Bamboo Slab byg:bambooslab to the ore dictionary using CraftTweaker.

Crash Log

Script Used:

val logWood=<ore:logWood>;
val slabWood=<ore:slabWood>;
slabWood.add(<byg:bambooslab>);
logWood.add(<byg:bamboolog>);