Bug / Crash Cannot add new "Property groups"

[iopzxz]

I try to add new particle groups by pressing Edit and clicking + button


Then I am directed back to this page with errors

However particle groups has been added 

Though I can add particle group, the editor keeps glitching and pull me out of the edit mode each time I add or remove particle groups.
Following are list of detailed errors I get



Please help me to use this asset. I love your guys work.