Add defensive IsAlive check to Android ViewExtensions.OnUnloaded (#29934)

* Update ViewExtensions.cs

* Update ViewExtensions.cs

* Update ViewExtensions.cs

* - unsubscribe sooner

---------

Co-authored-by: Shane Neuville <[email protected]>

Author: jfversluis

src/Core/src/Platform/Android/ViewExtensions.cs

@@ -556,8 +556,10 @@ internal static IDisposable OnLoaded(this View view, Action action)
 			EventHandler<AView.ViewAttachedToWindowEventArgs>? routedEventHandler = null;
 			ActionDisposable? disposable = new ActionDisposable(() =>
 			{
-				if (routedEventHandler != null)
+				if (routedEventHandler is not null && view.IsAlive())
+				{
 					view.ViewAttachedToWindow -= routedEventHandler;
+				}
 			});
 
 			routedEventHandler = (_, __) =>
@@ -596,16 +598,29 @@ internal static IDisposable OnUnloaded(this View view, Action action)
 			EventHandler<AView.ViewDetachedFromWindowEventArgs>? routedEventHandler = null;
 			ActionDisposable? disposable = new ActionDisposable(() =>
 			{
-				if (routedEventHandler != null)
+				if (routedEventHandler is not null)
 					view.ViewDetachedFromWindow -= routedEventHandler;
 			});
 
-			routedEventHandler = (_, __) =>
+			routedEventHandler = (sender,args) =>
 			{
 				// This event seems to fire prior to the view actually being
 				// detached from the window
 				if (view.IsLoaded() && Looper.MyLooper() is Looper q)
 				{
+					// We unsubscribe here because if we wait for the looper
+					// to schedule the work the view might get disposed by the time
+					// the unsubscribe code runs
+					if (disposable is not null)
+					{
+						if (args.DetachedView.IsAlive())
+						{
+							args.DetachedView.ViewDetachedFromWindow -= routedEventHandler;
+						}
+						
+						routedEventHandler = null;
+					}
+
 					new Handler(q).Post(() =>
 					{
 						if (disposable is not null)