I doubt it's my mod. I'm not in a position to debug it at this time. But its pointing to a line of code in my mod where I assign one of my own settings of my own mod. So I have no clue how that line of code ends up in a stack trace all the way to the other mod.
Only thing I can imagine is if their mod uses the same identifier of a UI item or setting that I have in use. There's naming conventions and recommendations to avoid those. Which I believe I am following at this point.
If I were in a position to try it. I could confirm it. But until then I'm in the impression the problem resides in the other mod. If they say the same thing, I'll happily debug this at a later date and see where it leads.