The app crashes when I set CanTearOutTabs="True" on the TabView

### Describe the bug

When I start the program and select one of the tabs, the program crashes.

### Steps to reproduce the bug

Create a new project with "Blank App, Packaged (WinUI 3 in Desktop)".

Edit MainWindow.xaml like this:

```

```

### Expected behavior

_No response_

### Screenshots

_No response_

### NuGet package version

Windows App SDK 1.6.1: 1.6.240923002

### Packaging type

Packaged (MSIX)

### Windows version

Windows 10 version 22H2 (19045, 2022 Update)

### IDE

Visual Studio 2022

### Additional context

_No response_

Start with the packaged WinUI 3 reproduction in MainWindow.xaml using TabView CanTearOutTabs="True", and run it on the reported Windows App SDK version. Confirm that selecting a tab reproduces the crash, then trace the TabView tear-out path and verify that tab selection no longer crashes.

Written by the indexing model from the issue text.