Issues with Javascript on Mac but not PC

i'm running strange issues script in user's mac halt on line nothing more store history state variable "acthist" while pcs run entire script fine.  we'll testing script mac later today, wondering if there known issues running java based scripts on macs vs pcs?  below screenshot of problem:

i can't figure out why stops on area.  tried asigning variable outside else statement cause out of ideas, same thing regardless declare it.  odd part is, same line used elsewhere in script without issues, not seem work in 1 spot on mac (pc has no issues it).  idea why problem mac , not pcs?

are documents in tabbed mode? preferences->interface->open documents tabs on vs off. think have issues scripting when *not* in tabbed mode.

More discussions in Photoshop Scripting

adobe