Placing Custom Furniture down inside of a cabin when in coop will cause a crash for the host and/or connected player (It seems to be random which person crashes). This seems to not happen if you are alone in coop, just if there are multiple people.

Log: https://log.smapi.io/6ZSBE3WL

Steps to replicate (Was using Barfy's gaming TV):
Buy it from Robin (as a connected player), and then place it in your cabin.