Uncaught Error: cannot call methods on dialog before initialization; tried to call method ‘option’.

Problem/Motivation

Uncaught Error: cannot call methods on dialog prior to initialization; attempted to call method 'option'

Steps to reproduce

1) Set Bootstrap as the default theme;
2) Create a subtheme based on Bootstrap;
3) Create a web form and enable Ajax;
4) Display the form in a modal window;
5) Fill out and submit the form;
6) Check the developer console.

Proposed resolution

Remove logic in the contrib Bootstrap theme that adds the deprecated ‘ui-dialog-content’ class of the jQuery UI library and calls a Drupal Core behavior without options after the form submission.