Thank you for reporting the issues. The error messages are something that I'm actively trying to get rid of and already managed to remove a lot of them, but there are still some edge cases. When rebuilding the scripts in unity the editor loses the references to every private object I've created, so when that happens I have to recreate those lost objects. Normally I check for them before I use those objects, but there are a few things that I still need to add checks for, but if the errors do show it only happens for one frame, than the objects get recreated.
About the MacOs bug, unfortunately I can't test that out as I don't have a mac, but if you know how the problem could be solved, please let me know, so I can fix the issue.