Don't thrown when tap/selected is null, return null. For deselect. (#950)

Author: jamesmontemagno

src/CommunityToolkit/Xamarin.CommunityToolkit.UnitTests/Converters/ItemSelectedEventArgsConverter_Tests.cs

@@ -15,9 +15,10 @@ public class ItemSelectedEventArgsConverter_Tests
 		{
             // We know it's deprecated, still good to test it
 #pragma warning disable CS0618 // Type or member is obsolete
-            new object[] { new SelectedItemChangedEventArgs(expectedValue), expectedValue},
+            new object[] { new SelectedItemChangedEventArgs(expectedValue), expectedValue },
+			new object[] { null, null },
 #pragma warning restore CS0618 // Type or member is obsolete
-        };
+		};
 
 		[Theory]
 		[MemberData(nameof(GetData))]

src/CommunityToolkit/Xamarin.CommunityToolkit.UnitTests/Converters/ItemTappedEventArgsConverter_Tests.cs

@@ -15,9 +15,10 @@ public class ItemTappedEventArgsConverter_Tests
 			{
             // We know it's deprecated, still good to test it
 #pragma warning disable CS0618 // Type or member is obsolete
-                new object[] { new ItemTappedEventArgs(null, expectedValue), expectedValue},
+                new object[] { new ItemTappedEventArgs(null, expectedValue), expectedValue },
+                new object[] { new ItemTappedEventArgs(null, null), null },
 #pragma warning restore CS0618 // Type or member is obsolete
-            };
+			};
 
 		[Theory]
 		[MemberData(nameof(GetData))]

src/CommunityToolkit/Xamarin.CommunityToolkit/Converters/ItemSelectedEventArgsConverter.shared.cs

@@ -19,9 +19,14 @@ public class ItemSelectedEventArgsConverter : ValueConverterExtension, IValueCon
 		/// <param name="culture">The culture to use in the converter. This is not implemented.</param>
 		/// <returns>A <see cref="SelectedItemChangedEventArgs.SelectedItem"/> object from object of type <see cref="SelectedItemChangedEventArgs"/>.</returns>
 		public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
-		   => value is SelectedItemChangedEventArgs selectedItemChangedEventArgs
+		{
+			if (value == null)
+				return null;
+
+			return value is SelectedItemChangedEventArgs selectedItemChangedEventArgs
 			   ? selectedItemChangedEventArgs.SelectedItem
 			   : throw new ArgumentException("Expected value to be of type SelectedItemChangedEventArgs", nameof(value));
+		}
 
 		/// <summary>
 		/// This method is not implemented and will throw a <see cref="NotImplementedException"/>.

src/CommunityToolkit/Xamarin.CommunityToolkit/Converters/ItemTappedEventArgsConverter.shared.cs

@@ -19,9 +19,14 @@ public class ItemTappedEventArgsConverter : ValueConverterExtension, IValueConve
 		/// <param name="culture">The culture to use in the converter. This is not implemented.</param>
 		/// <returns>A <see cref="ItemTappedEventArgs.Item"/> object from object of type <see cref="ItemTappedEventArgs"/>.</returns>
 		public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
-			=> value is ItemTappedEventArgs itemTappedEventArgs
+		{
+			if (value == null)
+				return null;
+
+			return value is ItemTappedEventArgs itemTappedEventArgs
 				? itemTappedEventArgs.Item
 				: throw new ArgumentException("Expected value to be of type ItemTappedEventArgs", nameof(value));
+		}
 
 		/// <summary>
 		/// This method is not implemented and will throw a <see cref="NotImplementedException"/>.