[Preview 4] AV(Null) in SystemNavigationManager.GetForCurrentView()

Describe the bug Access violation to location 0x00000000. This should be a null pointer exception.

Steps to reproduce the bug

Steps to reproduce the behavior:

1. Create a blank WinUI 3 desktop app for Preview 4. Verifies that blank app works.
2. Install Microsoft.Toolkit.Uwp.UI.Controls 8.0.0-preview4 from their feed.
3. Add a blank MasterDetailsView to main window.
4. Exception thrown when the MasterDetailsView is loaded.

Expected behavior Shows without exception.

Version Info

NuGet package version:

Microsoft.WinUI 3.0.0-preview4.210210.4 Not seeing in preview3 or preview2.

Windows app type:

UWP	Win32
	Yes

Windows 10 version	Saw the problem?
Insider Build (xxxxx)
October 2020 Update (19042)	Yes
May 2020 Update (19041)
November 2019 Update (18363)
May 2019 Update (18362)
October 2018 Update (17763)
April 2018 Update (17134)
Fall Creators Update (16299)
Creators Update (15063)

Device form factor	Saw the problem?
Desktop	Yes
Xbox
Surface Hub
IoT

Additional context Stack trace:

 	CoreUIComponents.dll!Microsoft::WRL::ComPtr<Windows::UI::Core::ICoreWindow>::As<ICoreWindowInterop>()	未知
 	CoreUIComponents.dll!Windows::UI::Core::SystemNavigationManagerStatics::GetForCurrentView()	未知
 	[托管到本机的转换]	
 	Microsoft.Windows.SDK.NET.dll!ABI.Windows.UI.Core.ISystemNavigationManagerStatics.Windows.UI.Core.ISystemNavigationManagerStatics.GetForCurrentView()	未知
 	Microsoft.Windows.SDK.NET.dll!Windows.UI.Core.SystemNavigationManager.GetForCurrentView()	未知
 	Microsoft.Toolkit.Uwp.UI.Controls.dll!Microsoft.Toolkit.Uwp.UI.Controls.MasterDetailsView.OnLoaded(object sender, Microsoft.UI.Xaml.RoutedEventArgs e)	未知

WCTK side may be updated to guard for using it. But WinUI side should gracefully return null or something other than crash with null AV.

[huoyaoyuan]

This is currently blocking MasterDetailsView totally.

[huoyaoyuan]

Hello, the same issue is blocking ListDetailView (renamed from MasterDetailsView) again, in WinUI/WAS 1.0.0-preview3. @michael-hawker @Austin-Lamb