Hi Jeff,
sounds like the update was botched. If "all of the HotPots that were there disappeared", then it seems the Moodle administrator deleted the HotPot module before via Moodle the interface before installing the new version of the HotPot module.
To investigate the error message, please set Moodle debugging (Site administration -> Development -> Debugging) to "Developer" and enable "Display debug message", and report the full error output. I need to know which line of which PHP script generates the error.
cheers
Gordon