unset variable causing image editing problem

In Mantra (and other themes) there is a problem with this code:

function mantra_dynamic_editor_styles($settings){
$settings[‘content_css’] .= “,”.admin_url(‘admin-ajax.php’) .”/?action=dynamic_styles”;
return $settings;
}

it should be:

function mantra_dynamic_editor_styles($settings){
if ( isset( $settings[‘content_css’] ) ) {
$settings[‘content_css’] .= “,”.admin_url(‘admin-ajax.php’) .”/?action=dynamic_styles”;
}
return $settings;
}

This should solve these problems: https://www.cryoutcreations.eu/forums/t/found-bug-image-in-post-will-not-edit-when-using-these-two-popular-plug-ins

https://www.ads-software.com/support/topic/black-studio-tinymce-widget-edit-image-conflict?replies=1

https://www.ads-software.com/support/topic/conflict-with-page-builder-reimage-edit?replies=7