Fails when Object property unset then resaved.

If we have an $object, then set a property and then store in queryable variables, then unset the property and try to restore the object we get..

warning: Invalid argument supplied for foreach() in C:\Program Files (x86)\Zend\Apache2\htdocs\in-seine\sites\all\modules\queryable_variables\queryable_variables.module on line 371.

that's because $elements is now NULL and fails the foreach.

Fix.. Simple check to make sure $elements is not null before proceeding into the evaluation of it. This works for me. Needs testing.