detecting payment has been cancelled.

[ambrose-at-cordic]

How do you detected if a payment has been cancelled or user has pressed the back button on the connection / payment screen? We have implemented logic to handle failed payment due to network issue, etc, but as of SumUp SDK v3.2.0, whether the payment was cancelled, back button was pressed on the connection/payment screens or the payment failed due to network connectivity, the result code from the response always comes back as ERROR_TRANSACTION_FAILED, which isn't that helpful.