Make sure options are defined after optClone

lib/model.js

@@ -2256,6 +2256,7 @@ module.exports = (function() {
   };
 
   var optClone = Model.prototype.__optClone = function(options) {
+    options = options || {};
     return Utils.cloneDeep(options, function(elem) {
       // The InstanceFactories used for include are pass by ref, so don't clone them.
       if (elem &&