Fix bug in C# find references.

src/AddIns/BackendBindings/CSharpBinding/Project/Src/Parser/CSharpSymbolSearch.cs

@@ -108,7 +108,7 @@ namespace CSharpBinding
 						highlighter = SD.EditorControlService.CreateHighlighter(document);
 					}
 					Identifier identifier = node.GetChildByRole(Roles.Identifier);
-					if (identifier != null)
+					if (!identifier.IsNull)
 						node = identifier;
 					var region = new DomRegion(fileName, node.StartLocation, node.EndLocation);
 					int offset = document.GetOffset(node.StartLocation);
@@ -117,6 +117,7 @@ namespace CSharpBinding
 					var defaultTextColor = highlighter != null ? highlighter.DefaultTextColor : null;
 					results.Add(new Reference(region, result, offset, length, builder, defaultTextColor));
 				}, cancellationToken);
+			if (results.Count > 0)
 				callback(new SearchedFile(fileName, results));
 		}
 	}