Turns out yes, i did miss it.
Where i have nullified something causes this error, i am not sure what to put in that slot
https://github.com/NicosaurusRex99/farts/blob/1.12.2/src/main/java/naturix/farts/network/PacketSendKey.java#L50
https://gist.github.com/NicosaurusRex99/230851c4c0411485a67e10d008061a3f