Merge pull request 'Fix automatically showing next feed on catchup' (#25) from wn/tt-rss:bugfix/on-catchup-show-next-feed into master

Reviewed-on: https://git.tt-rss.org/fox/tt-rss/pulls/25

js/Feeds.js

@@ -479,10 +479,10 @@ const	Feeds = {
 
 			// only select next unread feed if catching up entirely (as opposed to last week etc)
 			if (show_next_feed && !mode) {
-				const nuf = this.getNextUnread(feed, is_cat);
+				const [next_feed, next_is_cat] = this.getNextUnread(feed, is_cat);
 
-				if (nuf) {
-					this.open({feed: nuf, is_cat: is_cat});
+				if (next_feed !== false) {
+					this.open({feed: next_feed, is_cat: next_is_cat});
 				}
 			} else if (feed == this.getActive() && is_cat == this.activeIsCat()) {
 				this.reloadCurrent();