I'm implementing a mesh subsystem provider to run in the editor. On exiting play mode I get these errors:

ArgumentNullException: Value cannot be null.
Parameter name: _unity_self
UnityEngine.XR.XRMeshSubsystem.TryGetMeshInfos (System.Collections.Generic.List`1[T] meshInfosOut) (at /Users/bokken/buildslave/unity/build/Modules/XR/Subsystems/Meshing/XRMeshSubsystem.bindings.cs:204)
UnityEngine.XR.ARFoundation.ARMeshManager.UpdateMeshInfos () (at Library/PackageCache/com.unity.xr.arfoundation@4.1.7/Runtime/AR/ARMeshManager.cs:343)
UnityEngine.XR.ARFoundation.ARMeshManager.Update () (at Library/PackageCache/com.unity.xr.arfoundation@4.1.7/Runtime/AR/ARMeshManager.cs:251)

ArgumentNullException: Value cannot be null.
Parameter name: _unity_self
UnityEngine.XR.ARFoundation.ARMeshManager.OnDisable () (at Library/PackageCache/com.unity.xr.arfoundation@4.1.7/Runtime/AR/ARMeshManager.cs:380)

My subsystem has already been shutdown but the mesh manager is still trying to access it.

Reproduced in both 2019.4.29f1 and 2021.1.17f1 with ARF 4.1.7