remove unnecessary checks

src/categories.js

@@ -31,7 +31,7 @@ Categories.getCategoryById = function (data, callback) {
 			Categories.getCategories([data.cid], data.uid, next);
 		},
 		function (categories, next) {
-			if (!Array.isArray(categories) || !categories[0]) {
+			if (!categories[0]) {
 				return next(new Error('[[error:invalid-cid]]'));
 			}
 			category = categories[0];

src/controllers/topics.js

@@ -314,7 +314,7 @@ topicsController.teaser = function (req, res, next) {
 			posts.getPostSummaryByPids([pid], req.uid, { stripTags: false }, next);
 		},
 		function (posts) {
-			if (!Array.isArray(posts) || !posts.length) {
+			if (!posts.length) {
 				return res.status(404).json('not-found');
 			}
 			res.json(posts[0]);

src/groups/delete.js

@@ -14,7 +14,7 @@ module.exports = function (Groups) {
 				Groups.getGroupsData([groupName], next);
 			},
 			function (groupsData, next) {
-				if (!Array.isArray(groupsData) || !groupsData[0]) {
+				if (!groupsData[0]) {
 					return callback();
 				}
 				groupObj = groupsData[0];

src/notifications.js

@@ -363,10 +363,6 @@ Notifications.markAllRead = function (uid, callback) {
 			db.getSortedSetRevRange('uid:' + uid + ':notifications:unread', 0, 99, next);
 		},
 		function (nids, next) {
-			if (!Array.isArray(nids) || !nids.length) {
-				return next();
-			}
-
 			Notifications.markReadMultiple(nids, uid, next);
 		},
 	], callback);

src/topics.js

@@ -235,7 +235,7 @@ var social = require('./social');
 				posts.getPidsFromSet(set, start, stop, reverse, next);
 			},
 			function (pids, next) {
-				if ((!Array.isArray(pids) || !pids.length) && !topic.mainPid) {
+				if (!pids.length && !topic.mainPid) {
 					return callback(null, []);
 				}
 

src/topics/follow.js

@@ -200,16 +200,10 @@ module.exports = function (Topics) {
 				Topics.getFollowers(postData.topic.tid, next);
 			},
 			function (followers, next) {
-				if (!Array.isArray(followers) || !followers.length) {
-					return callback();
-				}
 				var index = followers.indexOf(exceptUid.toString());
 				if (index !== -1) {
 					followers.splice(index, 1);
 				}
-				if (!followers.length) {
-					return callback();
-				}
 
 				privileges.topics.filterUids('read', postData.topic.tid, followers, next);
 			},

src/user/notifications.js

@@ -271,9 +271,6 @@ UserNotifications.sendTopicNotificationToFollowers = function (uid, topicData, p
 			db.getSortedSetRange('followers:' + uid, 0, -1, next);
 		},
 		function (followers, next) {
-			if (!Array.isArray(followers) || !followers.length) {
-				return;
-			}
 			privileges.categories.filterUids('read', topicData.cid, followers, next);
 		},
 		function (_followers, next) {