How to reproduce:
1. Open user-submitted project (ResourceLoadDeadLock.zip)
2. Open the SampleScene
3. Enter Play Mode
4. Click the button in the middle of Game View
Expected result: the Editor does not freeze
Actual result: the Editor becomes unresponsive
Reproducible with: 2018.4.26f1, 2019.4.9f1, 2020.1.3f1, 2020.2.0a21