*Steps to reproduce:*
# Create a new project (in my case, I used Unity 6000.0.24f1).
# Install the [Behavior Demo|https://assetstore.unity.com/packages/templates/tutorials/behavior-demo-for-unity-298313] package.
# Add the [SceneBootstrapper|https://github.com/Unity-Technologies/com.unity.multiplayer.samples.coop/blob/main/Assets/Scripts/Editor/SceneBootstrapper.cs] script.
# Check if the “Bootstrapper” scene is the first in the Scene List.
# Open a different scene, as the script will not run if it is already loaded.
# Press play, wait a moment, and then press stop.
# Close the project and open it again (the issue can happen without restarting, but restarting increases the chances).
# 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