I was wandering around a woodland mansion when the game crashed with a null pointer exception. See the attached world download.

This may have causes a permanent lighting glitch, which I reported as MC-142048.

It's possible that this crash is responsible for the world save being huge, which you can find at https://drive.google.com/open?id=1FqWFm6d_nt7lAOp-q97VfU68BEWyEpZt. The room in question is at coordinates -13653 / 65 / -3035.