Return UnsetValue instead of throw exception'

As per winui docs https://docs.microsoft.com/en-us/uwp/api/windows.ui.xaml.dependencyproperty.unsetvalue?view=winrt-19041#remarks

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/EnumValuesExtension/AnimalToColorConverter.xaml.cs

@@ -5,6 +5,7 @@
 using System;
 using Microsoft.Toolkit.Uwp.SampleApp.Enums;
 using Windows.UI;
+using Windows.UI.Xaml;
 using Windows.UI.Xaml.Data;
 
 namespace Microsoft.Toolkit.Uwp.SampleApp.Converters
@@ -21,7 +22,7 @@ namespace Microsoft.Toolkit.Uwp.SampleApp.Converters
                 Animal.Llama => Colors.Beige,
                 Animal.Parrot => Colors.YellowGreen,
                 Animal.Squirrel => Colors.SaddleBrown,
-                _ => throw new ArgumentException("Invalid value", nameof(value))
+                _ => DependencyProperty.UnsetValue
             };
         }
 

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/EnumValuesExtension/EnumValuesExtensionCode.bind

@@ -20,7 +20,7 @@ public sealed class AnimalToColorConverter : IValueConverter
             Animal.Bunny => Colors.Green,
             Animal.Parrot => Colors.YellowGreen,
             Animal.Squirrel => Colors.SaddleBrown,
-            _ => throw new ArgumentException("Invalid value", nameof(value))
+            _ => DependencyProperty.UnsetValue
         };
     }
 

Microsoft.Toolkit.Uwp.UI.Controls.Input/ColorPicker/ColorToColorShadeConverter.cs

@@ -5,6 +5,7 @@
 using System;
 using Microsoft.Toolkit.Uwp.Helpers;
 using Windows.UI;
+using Windows.UI.Xaml;
 using Windows.UI.Xaml.Data;
 using Windows.UI.Xaml.Media;
 
@@ -40,7 +41,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Controls.ColorPickerConverters
             }
             else
             {
-                throw new ArgumentException("Invalid color value provided");
+                return DependencyProperty.UnsetValue;
             }
 
             // Get the value component delta
@@ -50,7 +51,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Controls.ColorPickerConverters
             }
             catch
             {
-                throw new ArgumentException("Invalid parameter provided, unable to convert to integer");
+                return DependencyProperty.UnsetValue;
             }
 
             // Specially handle minimum (black) and maximum (white)

Microsoft.Toolkit.Uwp.UI.Controls.Input/ColorPicker/ColorToHexConverter.cs

@@ -5,6 +5,7 @@
 using System;
 using Microsoft.Toolkit.Uwp.Helpers;
 using Windows.UI;
+using Windows.UI.Xaml;
 using Windows.UI.Xaml.Data;
 using Windows.UI.Xaml.Media;
 
@@ -34,7 +35,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Controls.ColorPickerConverters
             }
             else
             {
-                throw new ArgumentException("Invalid color value provided");
+                return DependencyProperty.UnsetValue;
             }
 
             string hexColor = color.ToHex().Replace("#", string.Empty);

Microsoft.Toolkit.Uwp.UI.Controls.Input/ColorPicker/ContrastBrushConverter.cs

@@ -4,6 +4,7 @@
 
 using System;
 using Windows.UI;
+using Windows.UI.Xaml;
 using Windows.UI.Xaml.Data;
 using Windows.UI.Xaml.Media;
 
@@ -40,7 +41,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Controls.ColorPickerConverters
             }
             else
             {
-                throw new ArgumentException("Invalid color value provided");
+                return DependencyProperty.UnsetValue;
             }
 
             // Get the default color when transparency is high

Microsoft.Toolkit.Uwp.UI/Converters/ColorToDisplayNameConverter.cs

@@ -4,6 +4,7 @@
 
 using System;
 using Windows.UI;
+using Windows.UI.Xaml;
 using Windows.UI.Xaml.Data;
 using Windows.UI.Xaml.Media;
 
@@ -33,7 +34,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Converters
             }
             else
             {
-                throw new ArgumentException("Invalid color value provided");
+                return DependencyProperty.UnsetValue;
             }
 
             return ColorHelper.ToDisplayName(color);

Microsoft.Toolkit.Uwp.UI/Converters/TaskResultConverter.cs

@@ -4,6 +4,7 @@
 
 using System;
 using System.Threading.Tasks;
+using Windows.UI.Xaml;
 using Windows.UI.Xaml.Data;
 
 namespace Microsoft.Toolkit.Uwp.UI.Converters
@@ -26,7 +27,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Converters
                 return task.GetResultOrDefault();
             }
 
-            return null;
+            return DependencyProperty.UnsetValue;
         }
 
         /// <inheritdoc/>