I play with a mod called VanillaFix that will often notify the player of crashes that don't actually close the game. I got this one when I placed down a redstone read socket.

crash-2019-11-14_11.38.26-server.txt

EDIT: I've figured out that the issue occurs when you mouse over the read socket with WAILA which makes me think its an issue on their end.

WAILA apparently asked for "internal" Fluid Tanks / Inventory /Energy Buffers that are not bound to a specific side of the block and I forgot to handle that case properly (since these sockets don't have meaningful non side specific capabilities).