Logging out might cause a crash

[rastersize]

I tapped around a bit in the app and then tried to log out as the tag browser was just gray and then I got this nice little crash (when tapping the log out button):

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Children view controllers <OPFUserProfileViewController: 0x968eca0> and <OPFLoginViewController: 0x96df790> must have a common parent view controller when calling -[UIViewController transitionFromViewController:toViewController:duration:options:animations:completion:]'
*** First throw call stack:
(0x1ee6012 0x1783e7e 0x1ee5deb 0xdc0d58 0x4687a 0x4718d 0x1797705 0xcd32c0 0xcd3258 0xd94021 0xd9457f 0xd936e8 0xf971d3 0x1eaeafe 0x1eaea3d 0x1e8c7c2 0x1e8bf44 0x1e8be1b 0x25ad7e3 0x25ad668 0xccfffc 0x243d 0x2365 0x1)
libc++abi.dylib: terminate called throwing an exception

Stack trace isn’t of any interest as it’s more or less just main -> __pthread_kill.

/cc @tdeekens @makxan