update SearchEngine

MediaBrowser.Server.Implementations/Library/SearchEngine.cs

@@ -87,13 +87,16 @@ namespace MediaBrowser.Server.Implementations.Library
         {
             var searchTerm = query.SearchTerm;
 
+            if (searchTerm != null)
+            {
+                searchTerm = searchTerm.Trim().RemoveDiacritics();
+            }
+
             if (string.IsNullOrWhiteSpace(searchTerm))
             {
                 throw new ArgumentNullException("searchTerm");
             }
 
-            searchTerm = searchTerm.Trim().RemoveDiacritics();
-
             var terms = GetWords(searchTerm);
 
             var hints = new List<Tuple<BaseItem, string, int>>();