I'm getting a JS error in Firefox and Chrome on line 22. In Firefox it appears as,

$(".drupal-tabs:not(.tabs-processed)", context).find("> ul").tabs is not a function
[Break on this error] fx: fx

Wrapped the inside of Drupal.behaviors.tabs() in a try-catch is a simple way to work around it.

Comments

Same error here.
But the workaround simply prevents from using the feature...

I had this bug when using CTools.AJAX framework.
Once added Drupal.behaviors.tabs = function () {}; in Drupal.CTools.AJAX.CustomRespond now all works well.

This method does not work if AJAX contains tabs.