Widgets don’t work when pdf embedder is installed

Kadence theme and pdf embedder – now can’t edit widgets anymore. Here is the email alert we get:
Error Details
=============
An error of type E_ERROR was caused in line 602 of the file /var/www/vhosts/myaddress.fi/httpdocs/wp-content/plugins/pdf-embedder/src/Admin/Admin.php. Error message: Uncaught TypeError: PDFEmbedder\Admin\Admin::render_page_footer(): Argument #1 ($text) must be of type string, null given, called in /var/www/vhosts/myaddress.fi/httpdocs/wp-includes/class-wp-hook.php?on line 324 and defined in /var/www/vhosts/myaddress.fi/httpdocs/wp-content/plugins/pdf-embedder/src/Admin/Admin.php:602
Stack trace:
#0 /var/www/vhosts/myaddress.fi/httpdocs/wp-includes/class-wp-hook.php(324): PDFEmbedder\Admin\Admin->render_page_footer()
#1 /var/www/vhosts/myaddress.fi/httpdocs/wp-includes/plugin.php(205): WP_Hook->apply_filters()
#2 /var/www/vhosts/myaddress.fi/httpdocs/wp-admin/admin-footer.php(48): apply_filters()
#3 /var/www/vhosts/myaddress.fi/httpdocs/wp-admin/index.php(212): require_once(‘…’)
#4 {main}
?thrown