TextBox SelectAll Input Chinese crash

* .NET Core Version: .NET6
* Windows version: (`Windows10`)
* Does the bug reproduce also in WPF for .NET Framework 4.8?: Yes
*
Problem description:TextBox SelectAll Input Chinese crash

``` xaml



```

```C#
public MainWindow()
{
InitializeComponent();
//In actual business, sometimes I need to assign a string with a newline character
textEdit.Text = "testasdfasdfgasd阿斯顿发斯蒂芬\r\n撒旦法师打发斯蒂芬\r\n阿斯顿发送到发送到\r\n";
}
```

When there are multiple lines of strings, when using the Chinese input method to input, the selected text will crash directly
I know setting AcceptsReturn="True" UndoLimit!="0" will fix this
But I need to use Enter event, so it doesn't work for me
So how should I solve this problem?