I'm getting fatal error messages after uninstalling JChat Social. I don't understand how this is happening since there is no call to JChat live on my site that I am aware of. Here's the message I'm being emailed by my error catcher plugin:

RuposTel.com plg_system_fatal_catcher plugin detected a problem with your site.
Your site caused a blank screen upon a visit of this URL:
http://www.forrestastrology.com/index.php?option=com_jchat&format=json

Error message data:
1 Call to undefined method JDocumentJSON::isHtml5() in file: /xxxxx/public_html/libraries/joomla/document/html/renderer/head.php line: 66