When both the client and a dedicated server are running mystical, the client will crash on join. Apparently, the world is considered to not be a client world, and results in trying to get the haven manager when it's not possible (the PersistentState is not available to the client).
When both the client and a dedicated server are running mystical, the client will crash on join. Apparently, the world is considered to not be a client world, and results in trying to get the haven manager when it's not possible (the PersistentState is not available to the client).