XRRig throws NullPointerExceptions when rebuilding

[eisclimber]

Expected Behavior

No NullPointerExceptions should be thrown.

Current Behavior

After rebuilding a Scene with an ExPresS XR Rig inside the rig will throw NullPointerExceptions continously.

Possible Solution

Stop/Restart the Application in the editor.

Steps to Reproduce

1. Add an ExPresS XR Rig-GO to the Scene
2. Start the Application in the Editor
3. Change a bit of Code to force a rebuild whilst the Application is running in the Editor
4. Exceptions should be thrown continuously

Context (Environment)

This Exception should be prevented, as it might confuse programmers. As of right now the source of the problem was not found and thus needs further investigation.