Don't save/log websocket error

It's a generic error Event and doesn't actually contain anything useful.

// FREEBIE

libtextsecure/message_receiver.js

@@ -48,8 +48,7 @@
             console.log('websocket open');
         },
         onerror: function(error) {
-            console.log('websocket error', error);
-            this.socketError = error;
+            console.log('websocket error');
         },
         onclose: function(ev) {
             var eventTarget = this;