Ben – see https://gist.github.com/jb510/0f31cdf0c667e983c94cfc290a6fc23b

wp_get_nav_menu_object() will return “false” ( a non-object ) when it’s empty… you just need to check that before continuing, more performant that way too 😀

$menu = wp_get_nav_menu_object( $locations[ $menu_name ] );
if (false != $menu) {
	$menu_items = wp_get_nav_menu_items( $menu->term_id );

	foreach( (array) $menu_items as $key => $menu_item ) {
[snip]
		} // end foreach
	} // end if
} // end menu1 - site-name menu