Fatal error when preloading via cron

I get a fatal error when I try to call the URL …?action=wpfastestcache&type=preload

The error message is:

Fatal error: Uncaught Error: Call to a member function get_extra_permastruct() on null in / .../wp-includes/taxonomy.php:4077 Stack trace: #0 / .../wp-content/plugins/wp-fastest-cache/wpFastestCache.php(1235): get_term_link(Object(WP_Term), 'category') #1 / .../wp-content/plugins/wp-fastest-cache/wpFastestCache.php(156): WpFastestCache->create_preload_cache() #2 / .../wp-content/plugins/wp-fastest-cache/wpFastestCache.php(1680): WpFastestCache->__construct() #3 / .../wp-settings.php(273): include_once('/data/web/virtu...') #4 / .../wp-config.php(99): require_once('/data/web/virtu...') #5 / .../u in / .../wp-includes/taxonomy.php on line 4077

When I ran the preload before, there was no error.
(with PHP 7)