fix: Use FallbackColor for unsupported brushes

Previously we have thrown Application.UnhandledException when an unsupported brush was used, even though we still had FallbackColorWithOpacity available

src/Uno.UI/UI/Xaml/Shapes/Shape.iOSmacOS.cs

@@ -102,8 +102,15 @@ private void SetFillAndStroke(CAShapeLayer pathLayer)
 					fillColor = Colors.Transparent;
 					break;
 
+				case XamlCompositionBrushBase compositionBrush: // Use Fallback for unsupported brushes
+					fillColor = compositionBrush.FallbackColorWithOpacity;
+					break;
+
 				default:
-					Application.Current.RaiseRecoverableUnhandledException(new NotSupportedException($"The brush {Fill} is not supported as Fill for a {this} on this platform."));
+					if (this.Log().IsEnabled(LogLevel.Warning))
+					{
+						this.Log().LogWarning($"The brush {Fill} is not supported as Fill for a {this} on this platform.");
+					}
 					fillColor = Colors.Transparent;
 					break;
 			}