Fix referral bug

lib/interceptor.js

@@ -66,7 +66,7 @@ var Interceptor = new Class({
         httpChannel.setRequestHeader('Referer', null, false);
 
         // Temporary fix for reported issues with the Play Store website.
-        if (httpChannel.referrer.host === 'play.google.com') {
+        if (httpChannel.referrer && httpChannel.referrer.host === 'play.google.com') {
             this.handleMissingCandidate(httpChannel);
             return;
         }