How to reproduce:
1. Open the attached project or download "Toy Car Game" from Asset Store
2. Notice that it has one compilation error and leave it
3. Select TCar-> 2Prefabs -> Shells -> CarBus1 in Assets folder
Result: If you check Inspector, you should notice broken GUI. Also check Console there will be 2 types of errors spammed ArgumentNullException: Argument cannot be null.; GUI Error: You are pushing more GUIClips than you are popping. Make sure they are balanced);

Note: If one deletes the line of code which causes this error, this prefab won't have any issues

Reproducible: 2017.2.0b3
Not reproducible: 2017.1.0f3