fix folder cleanup check

ErsatzTV.Application/Maintenance/Commands/DeleteOrphanedArtworkHandler.cs

@@ -153,13 +153,16 @@ public class DeleteOrphanedArtworkHandler(
         {
             try
             {
-                // don't delete direct children of artwork cache folder
+                // don't delete artwork cache folder or its direct children
+                if (path != FileSystemLayout.ArtworkCacheFolder)
+                {
                     var parent = fileSystem.Directory.GetParent(path);
-                if (parent != null && parent.FullName != FileSystemLayout.ArtworkCacheFolder)
+                    if (parent?.FullName != FileSystemLayout.ArtworkCacheFolder)
                     {
                         fileSystem.Directory.Delete(path);
                     }
                 }
+            }
             catch (Exception ex)
             {
                 logger.LogWarning(ex, "Could not delete empty cache folder {Folder}", path);