Reply To: thank you page changes

it appears that apparently on functions.php this causes the issue of breaakdown and of the 3 errors reported above.
add_action( ‘woocommerce_thankyou’, ‘custom_woocommerce_auto_complete_order’ );

function custom_woocommerce_auto_complete_order( $order_id ) {
if ( ! $order_id ) {
return;
}

$order = wc_get_order( $order_id );

if ( $order && ‘cod’ === $order->get_payment_method() ) {
$order->update_status( ‘completed’ );
}
}
i am struggling to find something like this but with no success.
any idea what to apply in order to accomplish automatic set of order to completed status?
thanks in advance!