Creating default object from empty value (in shipping modules)

[lat9]

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.

Just a quick note that your site is an accident waiting to happen. Zen Cart v1.3.9h doesn't include the changes that are required for the PHP interface changes made to the built-in htmlspecialchars and htmlentities functions starting with PHP 5.4 -- the default character set changed from (essentially) ASCII to UTF-8.