Magento CE 18.104.22.168
Working on a new client's site and I've been assigned the task of disabling and removing Sonassi WordPress Deluxe extension. I proceed to edit app/etc/modules/Sonassi_WordpressDeluxe.xml by changing active from true to false, then I clear cache. The frontend of the site continues to operate normally but when I attempt to access the admin URL, Magento renders the homepage with a new message showing in a Mage_Core_Block_Messages block that says:
Magento has detected a fatal error (get_class() expects parameter 1 to be object, boolean given)
None of my var/ logs or PHP logs show any reference to this and the full page from header to footer loads. To me this implies that they have copied some of the extension code into the theme directories but I'm not sure. What is the most effective way to proceed with debugging?