dont do anything if id is falsy

added callback

src/database/mongo/main.js

@@ -41,6 +41,9 @@ module.exports = function(db, module) {
 
 	module.searchRemove = function(key, id, callback) {
 		callback = callback || helpers.noop;
+		if (!id) {
+			return callback();
+		}
 		db.collection('search').remove({key: key, id: id}, callback);
 	};
 

src/database/redis/main.js

@@ -26,6 +26,11 @@ module.exports = function(redisClient, module) {
 	};
 
 	module.searchRemove = function(key, id, callback) {
+		callback = callback || function() {};
+		if (!id) {
+			return callback();
+		}
+
 		if (key === 'post') {
 			module.postSearch.remove(id, callback);
 		} else if(key === 'topic') {