I get this error on every page if I disable a product while it's in a cart. Only way to fix it is to clear browser cache and cookies.
I know there are already a lot of answers about this saying to increase
xdebug.max_nesting_level in php.ini, but I don't have anything xdebug related in php.ini.
vagrant@penn:~$ php -v PHP 5.5.9-1ubuntu4.14 (cli) (built: Oct 28 2015 01:34:46) Copyright (c) 1997-2014 The PHP Group Zend Engine v2.5.0, Copyright (c) 1998-2014 Zend Technologies with Zend OPcache v7.0.3, Copyright (c) 1999-2014, by Zend Technologies with Xdebug v2.2.3, Copyright (c) 2002-2013, by Derick Rethans
What should I do?