Merge pull request #4789 from crobibero/provider-search

Fix get provider id extension

(cherry picked from commit bc8f1bdcac)
Signed-off-by: Joshua M. Boniface <joshua@boniface.me>

MediaBrowser.Model/Entities/ProviderIdsExtensions.cs

@@ -49,7 +49,7 @@ namespace MediaBrowser.Model.Entities
             }
 
             instance.ProviderIds.TryGetValue(name, out string? id);
-            return id;
+            return string.IsNullOrEmpty(id) ? null : id;
         }
 
         /// <summary>