It is a tricky one. It looks like an object is released while it is still in a dictionary. Something like that should not happen in Swift. I need to review that as it may be caused by concurrent access to the array.
Andrzej Wójcik (Tigase) commented 5 years ago
A possible fix is applied and new build 3.1b33 is now available at DropBox
Issue reported by Artur: