PHP Error if Menu module is disabled

After a fresh Drupal 7 install, when enabling the starterkit theme (after moving it out of the Zen folder and renamed the .info.txt file to .info), the following error occurs if the Menu module is not enabled (which is not in a minimal installed):

PHP Fatal error: Call to undefined function menu_get_menus() in /var/www/drupal-7.0/sites/all/themes/zen/template.php on line 226, referer: http://localhost/drupal-7.0/?q=admin/appearance

zen/template.php:
function zen_preprocess_page(&$variables, $hook) {
// Find the title of the menu used by the secondary links.
$secondary_links = variable_get('menu_secondary_links_source', 'user-menu');
$menus = menu_get_menus(); // Line 226
$variables['secondary_menu_heading'] = $menus[$secondary_links];
}

I enabled the Menu module and moved on, but I figured this should be documented.