The las error line that is logged in the error stack trace is:
Code:
m_ItemCollections = new List<ItemCollection>();
...And for some reason that triggers an on validate callback in the serialization class... I have no clue why or why that returns an error.
If this error ever appears again do let us know and send us the full error log: https://docs.unity3d.com/Manual/LogFiles.html
And tell us how you were able to replicate it such that we may try to replicate it on our machines
I spent a few hours trying to figure out what I did to cause this to happened and came up with nothing. I ended up just rolling back my project but I will 100% keep my eyes out. I love your work and would be cool to help out in any way to make it better.