FIS WorldPay Vantiv Express refund and void status on provider errors

FIS WorldPay Vantiv Express refunds and voids now settle to a clear transaction status when the gateway returns an incomplete error, no response, or response code 15, instead of stalling in REFUNDING or failing while reading the payload.

• Malformed or empty provider error payloads no longer cause an internal failure mid-refund or void; the transaction moves to a reconciliable status.
• Missing provider responses during refund status refresh no longer leave the transaction stuck in REFUNDING.
• Response code 15 maps to refunded so completed refunds match what Worldpay reported.