Is there an existing issue for this?

• I have searched the existing issues

Did you read the "Reporting a bug" section on Contributing file?

• I have read the "Reporting a bug" section on Contributing file: https://github.com/CommunityToolkit/Maui.Markup/blob/main/CONTRIBUTING.md#reporting-a-bug

Current Behavior

Setting a bindable and nullable property to null throws an exception "Unable to find target value".

Expected Behavior

should be ok
this worked in "CommunityToolkit.Maui.Markup" Version="4.2.0"

Steps To Reproduce

In my case, the problem occurs in a special control.
The control is defined in nullable environment with generic struct to let a enum picker be set to null.

public partial class EnumPicker : Picker where T : struct, Enum //allow null with struct
...

the property is defined:

public static readonly BindableProperty SelectedValueProperty =
    BindableProperty.Create(
    nameof(SelectedValue),
    typeof(T?),
    typeof(EnumPicker<T>),
    null,
    BindingMode.TwoWay,
    null,
    propertyChanged: SelectedValue_Changed);

  public T? SelectedValue
  {
      get => (T?)GetValue(SelectedValueProperty);
      **set => SetValue(SelectedValueProperty, value);**
  }

The control is used at a contenview:

     enumPicker = new EnumPicker<T>()
     {
         Margin = new Thickness(0, 5, 0, 0),
         VerticalTextAlignment = TextAlignment.Center
     }
     .Bind(EnumPicker<T>.SelectedValueProperty,
         getter: static (EnumPickerControl<T> control) => control.SelectedValue,
         setter: static (EnumPickerControl<T> control, T? value) => control.SelectedValue = value,
         source: this);

After giving the Selected Value an enum value and set it back to null, the exception will be thrown at
set => SetValue(SelectedValueProperty, value);

Link to public reproduction project repository

hope this is not needed

Environment

- .NET MAUI C# Markup CommunityToolkit: 5.1.0
- CommunityToolkit.Maui: 10.0.0
- OS: Windows 10 Build 10.0.19041.0
- .NET MAUI: 9.0.21

Anything else?

Remove the exception throw in your TypedBinding.cs, Line 249:

var value = GetTargetValue(target.GetValue(property), typeof(TProperty))/* ?? throw new InvalidOperationException("Unable to find target value")*/;

returning a null is not a fault here. For my use, after removing the exception, it works than as it should.

More testing makes no sense for me, because i don't know the intention of throwing this exception here.