unify return values for getPreviousFeed and usages of both prev/next

js/App.js

@@ -938,16 +938,16 @@ const App = {
       } else {
 
          this.hotkey_actions["next_feed"] = () => {
-            const rv = dijit.byId("feedTree").getNextFeed(
+            const [feed, is_cat] = Feeds.getNextFeed(
                Feeds.getActive(), Feeds.activeIsCat());
 
-            if (rv) Feeds.open({feed: rv[0], is_cat: rv[1], delayed: true})
+            Feeds.open({feed: feed, is_cat: is_cat, delayed: true})
          };
          this.hotkey_actions["prev_feed"] = () => {
-            const rv = dijit.byId("feedTree").getPreviousFeed(
+            const [feed, is_cat] = Feeds.getPreviousFeed(
                Feeds.getActive(), Feeds.activeIsCat());
 
-            if (rv) Feeds.open({feed: rv[0], is_cat: rv[1], delayed: true})
+				Feeds.open({feed: feed, is_cat: is_cat, delayed: true})
          };
          this.hotkey_actions["next_article_or_scroll"] = (event) => {
             if (this.isCombinedMode())

js/FeedTree.js

@@ -435,7 +435,7 @@ define(["dojo/_base/declare", "dojo/dom-construct", "dojo/_base/array", "dojo/co
 			}
 
 			const items = this.model.store._arrayOfAllItems;
-			let item = items[0] == treeItem ? items[items.length-1] : items[0];
+			let item = false;
 
 			for (let i = 0; i < items.length; i++) {
 				if (items[i] == treeItem) {
@@ -453,7 +453,6 @@ define(["dojo/_base/declare", "dojo/dom-construct", "dojo/_base/array", "dojo/co
 								break;
 							}
 						}
-
 					}
 					break;
 				}
@@ -463,7 +462,7 @@ define(["dojo/_base/declare", "dojo/dom-construct", "dojo/_base/array", "dojo/co
 				return [this.model.store.getValue(item, 'bare_id'),
 					!this.model.store.getValue(item, 'id').match('FEED:')];
 			} else {
-				return false;
+				return [false, false];
 			}
 
 		},

js/Feeds.js

@@ -583,12 +583,26 @@ const	Feeds = {
 
 		return false;
 	},
+	getNextFeed: function(feed, is_cat) {
+		const tree = dijit.byId("feedTree");
+
+		if (tree) return tree.getNextFeed(feed, is_cat, false);
+
+		return [false, false];
+	},
+	getPreviousFeed: function(feed, is_cat) {
+		const tree = dijit.byId("feedTree");
+
+		if (tree) return tree.getPreviousFeed(feed, is_cat);
+
+		return [false, false];
+	},
 	getNextUnread: function(feed, is_cat) {
 		const tree = dijit.byId("feedTree");
 
 		if (tree) return tree.getNextUnread(feed, is_cat);
 
-		return false;
+		return [false, false];
 	},
 	search: function() {
 		xhr.json("backend.php",