[BUG] Something to do with sobgroups?

I just got this error:

luasobgroupquery 1145:  SobGroup_FillProximityPoint: could not find sobgroup (temp) 
parameter: bad argument #1 to `?' (string expected, got table) 
parameter: unable to recover; exiting

Yes, I was playing with my mod. But I checked and my mod does not use this function anywhere.