fix: skip library folders that are inaccessible or empty (#9291)

MediaBrowser.Controller/Providers/DirectoryService.cs

@@ -78,5 +78,10 @@ namespace MediaBrowser.Controller.Providers
 
             return filePaths;
         }
+
+        public bool IsAccessible(string path)
+        {
+            return _fileSystem.GetFileSystemEntryPaths(path).Any();
+        }
     }
 }

MediaBrowser.Controller/Providers/IDirectoryService.cs

@@ -16,5 +16,7 @@ namespace MediaBrowser.Controller.Providers
         IReadOnlyList<string> GetFilePaths(string path);
 
         IReadOnlyList<string> GetFilePaths(string path, bool clearCache, bool sort = false);
+
+        bool IsAccessible(string path);
     }
 }