dont crash sortedSetIncryBy on redis if no callback is supplied

src/database/mongo/helpers.js

@@ -1,6 +1,8 @@
 'use strict';
 
-var helpers = {};
+var helpers = module.exports;
+
+helpers.noop = function () {};
 
 helpers.toMap = function (data) {
 	var map = {};
@@ -31,7 +33,3 @@ helpers.valueToString = function (value) {
 
 	return value.toString();
 };
-
-helpers.noop = function () {};
-
-module.exports = helpers;

src/database/redis/helpers.js

@@ -2,6 +2,8 @@
 
 var helpers = module.exports;
 
+helpers.noop = function () {};
+
 helpers.multiKeys = function (redisClient, command, keys, callback) {
 	callback = callback || function () {};
 	var multi = redisClient.multi();

src/database/redis/sorted.js

@@ -180,6 +180,7 @@ module.exports = function (redisClient, module) {
 	};
 
 	module.sortedSetIncrBy = function (key, increment, value, callback) {
+		callback = callback || helpers.noop;
 		redisClient.zincrby(key, increment, value, function (err, newValue) {
 			callback(err, !err ? parseFloat(newValue) : undefined);
 		});