*Steps to reproduce:*

1.  Install Unity 6000.0.14f1 

2.  Create new template with the Mixed Reality template

3.  After the project boots up, the Project Validation tab will kick in and warn about a few issues with the project. Click Fix All and notice the crash.

*Actual results:* Crashes - here is the stack trace: 
========== OUTPUTTING STACK TRACE ==================0x00007FFBD9AC9AB2 (Unity) SerializableManagedRefTransfer::TransferScriptingObjectWithSerializedRefSupport<GenerateTypeTreeTransfer>
0x00007FFBD9AE0C0D (Unity) MonoBehaviour::VirtualRedirectTransfer
0x00007FFBD9BD0D55 (Unity) TypeTreeCache::GetTypeTree
0x00007FFBD9BBD704 (Unity) SerializedFile::SerializedType::CompareAgainstNewType
0x00007FFBD9BC4F2E (Unity) SerializedFile::ReadObject
0x00007FFBD9BC4CB6 (Unity) SerializedFile::ReadObject
0x00007FFBD9BAB4B4 (Unity) PersistentManager::ReadAndActivateObjectThreaded
0x00007FFBD9BA8788 (Unity) PersistentManager::LoadObjectsThreaded
0x00007FFBD9BA84F7 (Unity) PersistentManager::LoadObjects
0x00007FFBDB114E2E (Unity) ImportedAssetsReloadList::ReloadAssetInstances
0x00007FFBDB114F65 (Unity) ImportedAssetsReloadList::ReloadImportedAssetIfLoaded
0x00007FFBDB0643E6 (Unity) AssetImportManager::Import
0x00007FFBDB0421B0 (Unity) ImportOutOfDateAssets
0x00007FFBDB04AFA7 (Unity) RefreshInternalV2
0x00007FFBDB05434E (Unity) StopAssetImportingV2Internal
0x00007FFBDB04C10C (Unity) RefreshV2
0x00007FFBDB009830 (Unity) AssetDatabase::Refresh
0x00007FFBD91DD7D7 (Unity) AssetDatabase_CUSTOM_Refresh
0x000001D0C0C04892 (Mono JIT Code) (wrapper managed-to-native) UnityEditor.AssetDatabase:Refresh (UnityEditor.ImportAssetOptions)
0x000001D0C0C0473B (Mono JIT Code) UnityEditor.AssetDatabase:Refresh ()
0x000001D0C0C04653 (Mono JIT Code) UnityEditor.PackageManager.UI.Internal.AssetDatabaseProxy:Refresh ()
0x000001D0C0BF4565 (Mono JIT Code) UnityEditor.PackageManager.UI.Sample:Import (UnityEditor.PackageManager.UI.Sample/ImportOptions)
0x000001D0C0BF38DB (Mono JIT Code) [C:\Prototypes\mr\Assets\Samples\XR Interaction Toolkit\3.0.3\Hands Interaction Demo\Editor\Scripts\HandsInteractionSampleProjectValidation.cs:87] UnityEditor.XR.Interaction.Toolkit.Samples.Hands.HandsInteractionSampleProjectValidation/<>c:<.cctor>b__20_10 ()
0x000001D0C0B4A7D1 (Mono JIT Code) [.\Library\PackageCache\com.unity.xr.core-utils\Editor\ProjectValidation\BuildValidator.cs:156] Unity.XR.CoreUtils.Editor.BuildValidator:FixIssues (System.Collections.Generic.IList`1<Unity.XR.CoreUtils.Editor.BuildValidationRule>,string)
0x000001D0C0AD27A3 (Mono JIT Code) [.\Library\PackageCache\com.unity.xr.core-utils\Editor\ProjectValidation\ProjectValidationDrawer.cs:464] Unity.XR.CoreUtils.Editor.ProjectValidationDrawer:UpdateIssues (bool,bool)
0x000001D0C0AD21AB (Mono JIT Code) [.\Library\PackageCache\com.unity.xr.core-utils\Editor\ProjectValidation\ProjectValidationSettingsProvider.cs:45] Unity.XR.CoreUtils.Editor.ProjectValidationSettingsProvider:OnInspectorUpdate ()
0x000001D0C0AD204E (Mono JIT Code) UnityEditor.SettingsWindow:OnInspectorUpdate ()
0x000001D0C08429C0 (Mono JIT Code) UnityEditor.HostView:OnInspectorUpdate ()
0x000001CEC76B8488 (Mono JIT Code) (wrapper runtime-invoke) object:runtime_invoke_void__this__ (object,intptr,intptr,intptr)
0x00007FFC18D9697E (mono-2.0-bdwgc) [C:\build\output\Unity-Technologies\mono\mono\mini\mini-runtime.c:3445] mono_jit_runtime_invoke
0x00007FFC18CD8444 (mono-2.0-bdwgc) [C:\build\output\Unity-Technologies\mono\mono\metadata\object.c:3068] do_runtime_invoke
0x00007FFC18CD8530 (mono-2.0-bdwgc) [C:\build\output\Unity-Technologies\mono\mono\metadata\object.c:3115] mono_runtime_invoke
0x00007FFBD9B0F0F4 (Unity) scripting_method_invoke
0x00007FFBD9AE72B3 (Unity) ScriptingInvocation::Invoke
0x00007FFBD9AE739E (Unity) ScriptingInvocation::InvokeChecked
0x00007FFBD9B90E89 (Unity) SerializableManagedRef::CallMethod
0x00007FFBDAE0AEDD (Unity) WindowBehaviour::CallMonoMethod
0x00007FFBDAD20CB2 (Unity) SceneTracker::TickInspector
0x00007FFBDA86633D (Unity) Application::TickTimer
0x00007FFBDAE5D78A (Unity) MainMessageLoop
0x00007FFBDAE63462 (Unity) UnityMain
0x00007FF6B5ED2FBA (Unity) __scrt_common_main_seh
0x00007FFC7049257D (KERNEL32) BaseThreadInitThunk
0x00007FFC722AAF28 (ntdll) RtlUserThreadStart========== END OF STACKTRACE ===========

*Expected results:*  No crashes. Or ideally, the Template wouldn't boot up with issues to be fixed... 

*Reproducible with versions:* Unity 6000.0.10f1 or later

*Not reproducible with versions:* Unity 6000.0.7f1 or older, though the Project Validation tab doesn't kick in for these older versions.

*Reproduces on both Windows and MacOS*

*Tested on (OS):* 

*Notes:*
*