I made a server to show the mod to a friend, and we noticed that keeping to use Made in Heaven after the message "Heaven has begun" appeared makes the server crash after a few seconds. This problem doesn't seem to happen in singleplayer.

Link to the crash log: https://gist.github.com/giothemoonwalker/d0d5d12df31faf4d5c7390fd3f4cb9aa