Steps to reproduce the behavior:
-Install only ice and fire rotn version and library to see that there is the problem.
-On creative go to ice and fire blocks tab and try to see the pixies house.
-Complete! Your game is crashed.

Additionally i have tested that is the item the problem, the block placed looks to not crash the game (im still not sure).

part of much bigger problems of the fork which I'm getting back to rn, but I do know exactly what causes this error so no worries about that

Can you send the crash report

solved locally now, will be cleaning up a little more and then build and publish a patched version on CF

released a patched version on CF