Issue: Javascript error on index tab

When clicking the index tab when AJAX tabs are enabling and viewing a chapter of a Book, Firefox's Error Console shows a Javascript error. However, the page still redirects to the appropriate Book index article.

This occurs because when the window.location changes, all objects in the global scope are destroyed. For some reason, script execution continues while the browser waits for a server response, and the first time an object in the global scope is accessed, an error is thrown and then execution stops.

Fixed for the next build by using a bunch of returns when a tab calls for a refresh.