Reproduction steps:
1. Open the attached project “ReproProject“
2. Enable Mock Runtime in OpenXR settings tab (Project Settings → XR Plugin Management)
3. Enter Play Mode
4. Observe the result

Expected result: Play mode runs in mocked stereo rendering; possible to see what each eye would render, including occlusion mesh
Actual result: Project crashes

Reproducible in: 1.9.1 (2022.3.19f1) 1.14.1 (2022.3.60f1, 6000.0.44f1, 6000.1.0b12, 6000.2.0a7)

Reproducible on: Windows 11
Not reproducible on: No other environments tested

First few lines of the stack trace:

{noformat}0x00007FF9BE6A92B0 (OVRPlugin) UnityPluginUnload
0x00007FFA3BB14292 (UnityOpenXR) main_UnloadOpenXRLibrary
0x000002417E472187 (Mono JIT Code) (wrapper managed-to-native) UnityEngine.XR.OpenXR.OpenXRLoaderBase:Internal_PumpMessageLoop ()
0x000002417E4720C3 (Mono JIT Code) [.\Library\PackageCache\com.unity.xr.openxr@db4bbb5cd412\Runtime\OpenXRLoader.cs:319] UnityEngine.XR.OpenXR.OpenXRLoaderBase:ProcessOpenXRMessageLoop (){noformat}

Notes:

* If Editor stops Play Mode with an error “OpenXRFeature.enabled cannot be changed while OpenXR is running“, follow these steps: disable the Mock Runtime feature, enter Play Mode, exit Play Mode, re-enable the Mock Runtime feature, and then try to reproduce the issue again.
* If project did not crash after entering Play Mode, try to exit Play Mode to trigger the crash