CRITICAL Uncaught Error: Class “NumberFormatter” not found

My client has Accessibility Checker Pro but I don’t have the login for support on-hand at the moment so I’m posting this here.

The last few days in their Woocommerce logs I’m seeing this error:

CRITICAL Uncaught Error: Class "NumberFormatter" not found in /home/public_html/wp-content/plugins/accessibility-checker/includes/helper-functions.php:98

Stack trace:
#0 /home/public_html/wp-content/plugins/accessibility-checker/accessibility-checker.php(411): edac_ordinal(6.0)

#1 /home/public_html/wp-content/plugins/accessibility-checker/admin/class-ajax.php(75): edac_summary(771)

#2 /home/public_html/wp-includes/class-wp-hook.php(324): EDAC\Admin\Ajax->summary('')

#3 /home/public_html/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters('', Array)

#4 /home/public_html/wp-includes/plugin.php(517): WP_Hook->do_action(Array)

#5 /home/public_html/wp-admin/admin-ajax.php(188): do_action('wp_ajax_edac_su...')

#6 {main}
  thrown in /home/public_html/wp-content/plugins/accessibility-checker/includes/helper-functions.php on line 98