fix: counting the visible books can no longer close Libation

Both UIs recount from async void event handlers, where a failure is not a
faulted task anyone awaits but an unhandled exception. The count reads the file
system, so a Books folder on a drive that was just unplugged was enough to end
the session.

See issue #1984.

Co-authored-by: rmcrackan <rmcrackan@gmail.com>

Source/LibationAvalonia/ViewModels/MainVM.VisibleBooks.cs

@@ -199,8 +199,19 @@ partial class MainVM
 
 	private async Task setLiberatedVisibleMenuItemAsync()
 	{
-		var visible = ProductsDisplay.GetVisibleBookEntries();
-		var libraryStats = await Task.Run(() => LibraryCommands.GetCounts(visible));
-		await Dispatcher.UIThread.InvokeAsync(() => setVisibleNotLiberatedCount(libraryStats.PendingBooks));
+		try
+		{
+			var visible = ProductsDisplay.GetVisibleBookEntries();
+			var libraryStats = await Task.Run(() => LibraryCommands.GetCounts(visible));
+			await Dispatcher.UIThread.InvokeAsync(() => setVisibleNotLiberatedCount(libraryStats.PendingBooks));
+		}
+		// Every caller is an async void event handler, where a failure is not a faulted task anyone awaits but
+		// an unhandled exception that closes Libation. Counting these books reads the file system, which can
+		// fail at any moment for reasons that have nothing to do with the app - a Books folder on a drive that
+		// was just unplugged is enough. A stale number above a menu item is not worth the session.
+		catch (Exception ex)
+		{
+			Serilog.Log.Logger.Error(ex, "Error counting the visible books which are not yet liberated");
+		}
 	}
 }

Source/LibationWinForms/Form1.VisibleBooks.cs

@@ -28,6 +28,22 @@ public partial class Form1
 
 	private static DateTime lastVisibleCountUpdated;
 	void setLiberatedVisibleMenuItem()
+	{
+		try
+		{
+			setLiberatedVisibleMenuItemCore();
+		}
+		// Both callers are async void event handlers, where a failure is not a faulted task anyone awaits but
+		// an unhandled exception that closes Libation. Counting these books reads the file system, which can
+		// fail at any moment for reasons that have nothing to do with the app - a Books folder on a drive that
+		// was just unplugged is enough. A stale number above a menu item is not worth the session.
+		catch (Exception ex)
+		{
+			Serilog.Log.Logger.Error(ex, "Error counting the visible books which are not yet liberated");
+		}
+	}
+
+	private void setLiberatedVisibleMenuItemCore()
 	{
 		//Assume that all calls to update arrive in order,
 		//Only display results of the latest book count.