Call to undefined function wppa_make_tinymce_dialog()

WPPA+ seems to work correctly, but the PHP log is filled with this error:

PHP Fatal error:  Uncaught Error: Call to undefined function wppa_make_tinymce_dialog() in /var/www/html/wp-content/plugins/wp-photo-album-plus/wppa-ajax.php:1096
Stack trace:
#0 /var/www/html/wp-includes/class-wp-hook.php(353): wppa_ajax_callback()
#1 /var/www/html/wp-includes/class-wp-hook.php(377): WP_Hook->apply_filters()
#2 /var/www/html/wp-includes/plugin.php(523): WP_Hook->do_action()
#3 /var/www/html/wp-admin/admin-ajax.php(192): do_action()
#4 {main}
  thrown in /var/www/html/wp-content/plugins/wp-photo-album-plus/wppa-ajax.php on line 1096

Is this a known issue? I am using version 9.3.02.003