Repro steps:
1. Open project "Unity-AR-app.zip"
2. Install ARToolKit (from the toolbar)
3. Open "AR-one" scene
4. In Build Settings add "AR-one" scene to Scenes In Build
5. Open "Loading" scene
6. Press play
7. Wait till scene loads or open "AR-one" scene

Note: Problem is in awake function in ARController.cs script

Actual: ARToolKit asset causes scenes to crash on loading
Expected: ARToolKit asset should not cause scenes to crash on loading

Reproduced on: 5.3.6p8, 5.4.0f3, 5.5.0b11, 5.6.0a2