Fixed get with undefined objectId

Author: killme2008

lib/query.js

@@ -184,11 +184,17 @@
      * @param {Object} options A Backbone-style options object.
      */
     get: function(objectId, options) {
+      if(!objectId) {
+        var errorObject = new AV.Error(AV.Error.OBJECT_NOT_FOUND,
+                                          "Object not found.");
+        return AV.Promise.error(errorObject);
+      }
+
       var self = this;
       self.equalTo('objectId', objectId);
 
       return self.first().then(function(response) {
-        if (response) {
+        if (!AV._.isEmpty(response)) {
           return response;
         }