Undefined property: Craft\WebApp::$cache
Upon looking at the craft/runtime/logs/phperrors.log I noticed the following error being reported:

PHP Fatal error:  Maximum function nesting level of '200' reached, aborting! in /Users/username/path/to/website/craft/app/framework/base/CModule.php


To fix the issue, I updated the following line in my php.ini:

xdebug.max_nesting_level=200


To something higher:

xdebug.max_nesting_level=500


This error might be thrown in other scenarios as well as this fix seems pretty specific to having XDebug installed. In any case, these steps helped me get it resolved.