I’m having the same problem (crash right at the first vine wall on the helix). I get that weird MathRectValid error message, too. I assumed the problem was my Mac barely/not meeting the requirements to run the game, but it sounds like people with much better computers are having problems, too.
Mac OSX 10.12.6, Intel HD Graphics 4000 1536 MB, 4 GB RAM here. (Yes, playing on this thing is… trying, lol. I had a better computer for gaming when I first bought GW2.)
EDIT: I tried switching to windowed mode (I’d been playing fullscreen) and skipping the vine walls, and was able to get through.