Steps to reproduce:
1. Open QA attached project (reduced) or user attached project
2. Build and run for windows
3. Build will run, editor crashes

Expected: Building and running doesn't cause an editor crash
Actual: After build finishes and is run, the editor crashes

Reproduced on: 2017.2.0b3, 2017.2.0b5,
Regression itnroduced in: 2017.2.0b1
Doesn't reproduce on: 2017.2.0a4, 2017.1.0p2, 2017.1.0f3, 2017.1.0b1, 5.6.3f1

Note: Disabling Canvas -> MenuPanel-> RoomList Gameobjects "Mask (Script)" Component, prevents the crash.