tapesonthefloor

I have the exact same problem. Version 2.1.0.0 of Custom Sidebars on WordPress 4.0.

This js error occurs at admin_script.js:52 of plugin WP Twitter Feeds:

TypeError: settings.data.search is not a function

Pointing to the first line of this block of code:

if(settings.data.search('action=save-widget') != -1 ) {
    $('.intentColor .wp-picker-container').remove();
    updateColorPicker();
}

This happens even if no Twitter widgets are included in the sidebars. Disabling the Twitter Feeds plugin solves the issue.

Hope that helps!