Ignore non-existing customers when determining customer ID

[rvdsteege]

On payment start, we try to use the first existing Mollie customer ID:

wp-pronamic-pay-mollie/src/Gateway.php

Lines 1748 to 1754 in 1948c7f

	public function get_customer_id_for_payment( Payment $payment ) {
	$customer_ids = $this->get_customer_ids_for_payment( $payment );
	$customer_id = $this->get_first_existing_customer_id( $customer_ids );
	return $customer_id;
	}

wp-pronamic-pay-mollie/src/Gateway.php

Lines 1835 to 1855 in 1948c7f

	private function get_first_existing_customer_id( $customer_ids ) {
	$customer_ids = \array_filter( $customer_ids );
	$customer_ids = \array_unique( $customer_ids );
	foreach ( $customer_ids as $customer_id ) {
	try {
	$customer = $this->client->get_customer( $customer_id );
	} catch ( Error $error ) {
	// Check for status 410 ("Gone - The customer is no longer available").
	if ( 410 === $error->get_status() ) {
	continue;
	}
	throw $error;
	}
	if ( null !== $customer ) {
	return $customer_id;
	}
	}

Mollie returns the HTTP 410 'Gone' status if a customer does not exist anymore and we then ignore this customer ID. However, we do not store this permanent status and next time we test again for the existence of this customer ID.

I just ran into timeout issues in a development environment because of this. Manually truncating the wp_pronamic_pay_mollie_* database tables resolved the issue.

CC @remcotolsma