Sliced Invoices - change default ordering of quotes/invoices in admin list view

functions.php

// this will set default order by invoice/quote number

if ( is_admin() ) {
	add_action( 'pre_get_posts', 'sliced_set_default_orderby', 11 );
}

function sliced_set_default_orderby( $query ) {

	// double check to avoid interfering with any ajax requests
	if ( ! sliced_get_the_type() ) {
		return;
	}
	
	if ( ! isset( $_GET['order'] ) ) {
		$query->set('order','DESC');
	}

	if ( ! isset( $_GET['orderby'] ) ) {
		$query->set( 'meta_key', '_sliced_'.sliced_get_the_type().'_number' );  
        $query->set( 'orderby',  'meta_value_num' );
	}
	
}