How to reproduce:
1. Open the SampleScene in the attached "199488_minimal.zip" project
2. In hierarchy, select cube
3. In inspector, select Prefab "open"
4. Observe errors in console
5. Go back to scene ("Scenes" button at the top of scene view)
6. In hierarchy, select VOLUME
7. disable volume script component
8. Select Cube, open prefab
9. Observe no errors print

Expected results: "Cube" prefab is opened without any errors when a volume is active in the loaded scene
Actual results: "Cube" prefab is opened but rendered incorrectly because argumentNullExceptions are thrown, when a volume is active in the loaded scene

Reproducible with: 2020.1.0a14 (Universal RP 7.1.5)
Not reproducible with: 2020.1.0a14 (Universal RP 7.1.2)

Note: all ways to enter prefab mode are affected when there is a Volume present
Note: volume settings do not have an effect