Fix notification trigger

config/Windows/navigation.xml

 		/* Asynchronous notifications */
 		var DBUpdateNotifications = function() {
 			var query = new new QSqlQuery;
-			query.exec("CREATE OR REPLACE FUNCTION notify_roasting_log_change() RETURNS TRIGGER AS $$ BEGIN NOTIFY RoastingLogChange; END; $$ LANGUAGE plpgsql");
+			query.exec("CREATE OR REPLACE FUNCTION notify_roasting_log_change() RETURNS TRIGGER AS $$ BEGIN NOTIFY RoastingLogChange; RETURN NULL; END; $$ LANGUAGE plpgsql");
 			query.exec("CREATE TRIGGER notify_roasting_log_change AFTER INSERT OR UPDATE ON roasting_log FOR EACH STATEMENT EXECUTE PROCEDURE notify_roasting_log_change()");
 			query = query.invalidate();
 		};