message listener ignores non-string data

Author: danielstjules

lib/client.js

@@ -266,10 +266,12 @@
     this._listener = function(message) {
       var i, error, response;
 
-      if (client._closed) return;
-
-      // Ignore messages not from our hub
-      if (message.origin !== client._origin) return;
+      // Ignore invalid messages, those not from the correct hub, or when
+      // the client has closed
+      if (client._closed || !message.data || !message.data.indexOf ||
+          message.origin !== client._origin) {
+        return;
+      }
 
       // LocalStorage isn't available in the hub
       if (message.data === 'cross-storage:unavailable') {