[Bug] [XCT.Sample] Fixed ContentPages BackgroundColor (#1595)

* Removed SetAppThemeColor

* Move `BasePage` to `Pages` folder

* Handle Null Dereferences introduced in .NET 6

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

Author: 4 people

samples/XCT.Sample/Pages/Base/BasePage.cs

@@ -33,7 +33,6 @@ Forms.Page PreparePage(SectionModel model)
 			var page = (BasePage)Activator.CreateInstance(model.Type);
 			page.Title = model.Title;
 			page.DetailColor = model.Color;
-			page.SetAppThemeColor(BackgroundColorProperty, Color.White, Color.Black);
 			return page;
 		}
 	}

src/CommunityToolkit/Xamarin.CommunityToolkit/Views/DrawingView/Service/DrawingViewService.macos.cs

@@ -89,7 +89,8 @@ public static Stream GetImageStream(IList<Point>? points,
 
 			context.AddLines(points.Select(p => new CGPoint(p.X - minPointX, p.Y - minPointY)).ToArray());
 			context.StrokePath();
-			using var cgImage = context.ToImage() ?? throw new InvalidOperationException();
+
+			using var cgImage = context.ToImage() ?? throw new InvalidOperationException("Image Cannot be null");
 			NSImage image = new(cgImage, imageSize);
 
 			return image;
@@ -130,7 +131,7 @@ public static Stream GetImageStream(IList<Point>? points,
 
 			context.StrokePath();
 
-			using var cgImage = context.ToImage() ?? throw new InvalidOperationException();
+			using var cgImage = context.ToImage() ?? throw new InvalidOperationException("Image Cannot Be Null");
 			NSImage image = new(cgImage, imageSize);
 
 			return image;