I have no idea. I don't see anything wrong in the code in the screenshot, and considering that often an error won't show the real problem line, I'm guessing there's a problem with some other code that's messing things up further on. What had you just recently edited when the error appeared?
Ghan has said he has fixed this. Monovertex please confirm this fix. This was only a problem with people that had signatures in the upper levels like not the special members but the respected members.