change to ResetValidationTokenSource to guard against a disposed validationTokenSource (CommunityToolkit#2344)

* change to ResetValidationTokenSource to guard against a disposed validationTokenSource

* add .Dispose() after cancel()

---------

Co-authored-by: Pedro Jesus <pedrojesus.cefet@gmail.com>
Co-authored-by: Brandon Minnick <13558917+brminnick@users.noreply.github.com>

Author: 3 people

src/CommunityToolkit.Maui/Behaviors/Validators/ValidationBehavior.shared.cs

@@ -419,8 +419,16 @@ void UpdateStyle(in VisualElement view, bool isValid)
 
 	void ResetValidationTokenSource(CancellationTokenSource? newTokenSource)
 	{
-		validationTokenSource?.Cancel();
-		validationTokenSource = newTokenSource;
+		try
+		{
+			validationTokenSource?.Cancel();
+			validationTokenSource?.Dispose();
+		}
+		catch (ObjectDisposedException) { }
+		finally
+		{
+			validationTokenSource = newTokenSource;
+		}
 	}
 }