How to check for image tracking support in the Editor?

Unity Engine
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1

We’re building an app that shall support various platforms (Android, iOS, visionOS), so we want to check the existence of AR subsystems.

For Face Tracking, we use this approach:

var descriptors = new List<XRFaceSubsystemDescriptor>();
SubsystemManager.GetSubsystemDescriptors(descriptors);
if (descriptors.Any()) faceTrackingDescriptor = descriptors.First();

This works reliably, even in Unity Editor, where faceTrackingDescriptor is null, as expected.

However, if we try this for Image Tracking:

var descriptors = new List<XRImageTrackingSubsystemDescriptor>();
SubsystemManager.GetSubsystemDescriptors(descriptors);
if (descriptors.Any()) imageTrackingDescriptor = descriptors.First();

it returns a descriptor even in Unity Editor, indicating that Image Tracking should work here.

However, as soon as I call CreateRuntimeLibrary() on the ARTrackedImageManager, Unity throws an exception:

No image tracking subsystem found. This usually means image tracking is not supported.

This is super confusing. I assume this is a bug in ARFoundation. Is there another, more reliable (and non-hacky) way to detect if Image Tracking is available?

Edit: I found out that the property .descriptor on the ARTrackedImageManager itself is null in this case. However, on iOS, this is also null until I call CreateRuntimeLibrary on it. Then, the descriptor magically becomes available.