Hi notRitter!
I see that you are active at the moment so I take this opportunity to report my problem hoping to find a solution here.
The error occurs after returning to a map that contains a saved spawned event.
The bug disappears when I deactivate this plugin precisely.
https://drive.google.com/file/d/1JkIQm4yKJTWzNlDwu3-E67GuVIz544yr/view
I already tested it with "Ritter_EventSpawner SavedEvent Fix Testing".