Add null checks to EnsureDates

MediaBrowser.Controller/Resolvers/EntityResolutionHelper.cs

@@ -133,6 +133,19 @@ namespace MediaBrowser.Controller.Resolvers
         /// <param name="includeCreationTime">if set to <c>true</c> [include creation time].</param>
         public static void EnsureDates(IFileSystem fileSystem, BaseItem item, ItemResolveArgs args, bool includeCreationTime)
         {
+            if (fileSystem == null)
+            {
+                throw new ArgumentNullException("fileSystem");
+            }
+            if (item == null)
+            {
+                throw new ArgumentNullException("item");
+            }
+            if (args == null)
+            {
+                throw new ArgumentNullException("args");
+            }
+
             // See if a different path came out of the resolver than what went in
             if (!string.Equals(args.Path, item.Path, StringComparison.OrdinalIgnoreCase))
             {