message: new payment error code
diff: @@ -192,6 +192,9 @@ pub enum ErrorCode
  // Insufficient funds on inputs
  PaymentInsufficientFundsError = 702,
  +
  + // Extra funds on inputs
  + PaymentExtraFundsError = 705
  }
  impl ErrorCode {
  @@ -251,7 +254,8 @@ impl ErrorCode {
  DidAlreadyExistsError => "Did already exists",
  UnknownPaymentMethod => "Unknown payment method was given",
  IncompatiblePaymentError => "Multiple different payment methods were specified",
  - PaymentInsufficientFundsError => "Payment cannot be processed because there was insufficient funds"
  + PaymentInsufficientFundsError => "Payment cannot be processed because there was insufficient funds",
  + PaymentExtraFundsError => "Payment cannot be processed because there were more funds than required"
  }
  }
  