2018.4.5 HoloLens: Errors when stopping play mode

Hi,
After upgrading my HoloLens project from 2018.4.2 to 2018.4.5 I always get about 8 (apparently harmless) errors when I stop play mode in editor:

Number of tracked cameras doesn't match how many cameras we should have!

Spoiler: Current frame's back buffer doesn't exist! This should never happen, and this frame will likely be blank.

0x0000000141421AE8 (Unity) StackWalker::GetCurrentCallstack
0x0000000141427F96 (Unity) StackWalker::ShowCallstack
0x000000014130B16B (Unity) GetStacktrace
0x000000014014352E (Unity) DebugStringToFile
0x00000001419C1703 (Unity) HolographicRenderManager::UpdateTrackedCameras
0x00000001419C3C96 (Unity) VRDeviceHoloLens::EndFrameGfxThread
0x00000001419C85C1 (Unity) HoloLensEventGfxThreadCallback
0x00000001419A128D (Unity) VRDevice::SendVRDeviceEvent
0x0000000140B70740 (Unity) GfxDevice::SendVRDeviceEvent
0x0000000142225152 (Unity) GfxDeviceWorker::RunCommand
0x0000000142225D9B (Unity) GfxDeviceWorker::RunExt
0x0000000142225E94 (Unity) GfxDeviceWorker::RunGfxDeviceWorker
0x0000000140A78FF0 (Unity) Thread::RunThreadWrapper
0x00007FFD23714034 (KERNEL32) BaseThreadInitThunk
0x00007FFD23E83691 (ntdll) RtlUserThreadStart

Spoiler: Stopping the observer.

UnityEngine.Debug:Log(Object)
HoloToolkit.Unity.SpatialMapping.SpatialMappingObserver:StopObserving() (at Assets/HoloToolkit/SpatialMapping/Scripts/SpatialMappingObserver.cs:311)
HoloToolkit.Unity.SpatialMapping.SpatialMappingObserver:CleanupObserver() (at Assets/HoloToolkit/SpatialMapping/Scripts/SpatialMappingObserver.cs:326)
HoloToolkit.Unity.SpatialMapping.SpatialMappingObserver:OnDestroy() (at Assets/HoloToolkit/SpatialMapping/Scripts/SpatialMappingObserver.cs:510)

Unable to set holographic camera near plane
Unable to set holographic camera far plane
Can't update render data for the main HoloLens camera - render target size unavailable! Error code: '0x80004005'.
Unable to set holographic camera near plane
Unable to set holographic camera far plane
Can't update render data for the main HoloLens camera - render target size unavailable! Error code: '0x80004005'.

I am using the Emulation Mode Simulate in Editor.
It's not really a problem but somewhat annoying. It would be nice to get rid of them in a future version - thanks