v1.3.9h
PHP Version: 5.6.0
Database: MySQL 5.5.27-log

Starting yesterday, my customers are getting the same error message but in the shipping module.
PHP Warning: Creating default object from empty value in .........Cart\includes\modules\shipping_estimator.php on line 107 and once in line 117.

It only seems to happen when someone is not logged in.

I haven't changed anything and can't figure out why this started happening.