Launcher requests I report a 'fatal error'

I tried launching the game, was unexpectedly prompted to enter my username and password (I may have pressed a key, I don't think this was part of the bug), after which the launcher displayed a 'fatal error launching game' and requested I report this error here.

What I expected to happen was...:
I expected the game to launch.

What actually happened was...:
It did not launch, and displayed an error message instead. The game launched just fine after exiting out of the launcher and starting it again.

Steps to Reproduce:
Error does not appear to be reproducable. I would not have reported it had the launcher not specifically requested me to.

Attached is a .txt file with the information displayed in the launcher.