return empty on valid subreddit async

bot.js

@@ -157,6 +157,8 @@ function handleRedditJson(data) {
             return json.data.children[rand].data.url;
         }
     }
+    // What if we don't find anything i.e. r/dogs but its valid subreddit.
+    return "";
 }
 
 // Makes an async url request with the provided function: 'process'.