Reproduction steps:
1. Open the attached project ("1291053Repro.zip")
2. Make sure Graphics API is set as DX12 (Project Settings->Player->Other Settings)
3. Make sure Oculus XR Plugin is enabled (Project Settings->XR Plug-in Management)
4. Set Stereo Rendering Mode to Single Pass Instanced
5. Enter Play mode

Expected result: Oculus isn't initialized and a warning is thrown
Actual result: Editor crashes / HMD stucks on the application loading screen

Reproducible with: Oculus XR Plugin 1.5.0, 1.6.1, 1.7.0 (2019.4.18f1, 2020.2.2f1, 2021.1.0b2)
Could not test with: 2018.4.30f1 (XR SDK not available)

Tested:
- Oculus Rift S

Notes:
- Multi Pass Stereo Rendering mode does not crash and throws an error in the Console window
- When using Multi Pass HMD stucks on the application loading screen and a restart of the Editor is required