public static function defaultFilter($page)
    {
        // Exclude folders containing Kirby Modules
        // https://github.com/getkirby-plugins/modules-plugin
        $mod = C::get('modules.template.prefix', 'module.');
        if (Str::startsWith($page->intendedTemplate(), $mod)) {
            return [false, "Ignoring module pages (template prefix: \"$mod\")"];
        }
        // Exclude pages missing a content file
        // Note: $page->content()->exists() returns the wrong information,
        // so we use the inventory instead. For an empty directory, it can
        // be [] (single-language site) or ['code' => null] (multilang).
        if (array_shift($page->inventory()['content']) === null) {
            return [false, 'Page has no content file.'];
        }
        return true;
    }