Subscribe By Email Widget Javascript Error

The widget to allow users to Subscribe by Email is not working on our sites. There seems to be a javascript error and the form never processes. The wheel just spins. Checking the console, I see this error: Uncaught TypeError: Cannot read property 'length' of undefined for http://sites.uci.edu/syldev/wp-content/plugins/subscribe-by-email/assets/js/widget.js?ver=4.6.1