1. I do not get that error with Facebook. However, there are numerous Javascript errors related to jQuery. Can you try enabling JFBConnect's 'Load jQuery/Bootstrap' setting?
2. I do see the error on your page for Twitter. However, I attempted to go to
www.musicstartshere.org/index.php?option=com_users&task=login for the Joomla users component and received the same error, which leads me to believe this might be unrelated to JFBConnect. To verify, please disable all JFBC plugins (our system, authentication and login plugins), which effectively disables JFBConnect and see if the error still persists for the link I just gave. Let me know what you find.
-Melissa