I don't have my log file, but the error log was exactly the same as the one seen in Aang72's attachment.
Please post your log file because, Aang72's log shows he didn't had the latest version of the code, because the error references to a line number that has changed in the version currently online so, please post your log too, to be sure that (assuming you have updated with the FSDT Live Updater), the error still happens, likely with a different line number.
What I found was weird is that I did just that several times. It went away for awhile then happened again today. Though I think this one is related to editing the airport positions than running it (as I wasn't running any "active" things like boarding jetways etc). This has been an issue with this game overall (not just with GSX) so I am not blaming the crash on that.
(I have just updated today after it happened again so hopefully my theory stands)
