Steps to reproduce:

1. Create a new project (in my case, I used Unity 6000.0.24f1).
2. Install the Behavior Demo package.
3. Add the SceneBootstrapper script.
4. Check if the “Bootstrapper” scene is the first in the Scene List.
5. Open a different scene, as the script will not run if it is already loaded.
6. Press play, wait a moment, and then press stop.
7. Close the project and open it again (the issue can happen without restarting, but restarting increases the chances).
8. Press play again, and the errors should start to appear, with several NullReferenceExceptions showing up in the console.

Actual results: 

• NullReferenceExceptions are raised.

Expected results: 

• The package works well with the provided example.

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Reproducible with versions: 
Unity 6000.0.24f1
Not reproducible with versions: 
NA
Can’t test with versions: 
Below 6000.0.16f.

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Tested on (OS): 
Win