added imgur error handle

bot.js

@@ -128,8 +128,12 @@ function imgurRequest(subreddit, page_max) {
     req.onreadystatechange = function () {
         if (req.readyState === 4 && req.status === 200) {
             if (req.responseText !== "Not found") {
-                var json = JSON.parse(req.responseText);
-                returnText = json.data[getRandomInt(0, json.data.length - 1)].link;
+                try {
+                    var json = JSON.parse(req.responseText);
+                    returnText = json.data[getRandomInt(0, json.data.length - 1)].link;
+                } catch (error) {
+                    // Ignore the error and let the calling method handle the empty string.
+                }
             }
         }
     };