Working but with PHP Errors

Thank you both for reporting this.

What themes are you using, and are you using any other sidebar generator plugin?

If possible, can you try updating the file in question (wp-content/plugins/content-aware-sidebars/admin/admin_bar.php, line 155), by replacing

            $args[] = [
                'id'    => $index,
                'title' => $wp_registered_sidebars[$index]['name'] . ($has_widgets ? '' : ' ('.__('Hidden').')'),
            ];

with

            $sidebar_name = isset($wp_registered_sidebars[$index]['name'])
                ? $wp_registered_sidebars[$index]['name']
                : $index;
            $args[] = [
                'id'    => $index,
                'title' => $sidebar_name . ($has_widgets ? '' : ' ('.__('Hidden').')'),
            ];