Clarify unsupported transaction_data error

[andprian]

Clause 8.4. Transaction Data states: "If the wallet does not support transaction_data parameter, it MUST return an error."

Clarify what is the error that needs to be returned when transaction_data is not supported.

[babisRoutis]

To my understanding, there is not a dedicated error to express that the wallet doesn't support the transaction_data feature.

The invalid_transaction_data is the closest match, since it can be used in case transaction_data

contains an unknown or unsupported transaction data type value,

[Sakurann]

yes, we can clarify that invalid_transaction_data error must be returned.

To my understanding, there is not a dedicated error to express that the wallet doesn't support the transaction_data feature.

Yes, this is because we do not want the wallet to return credentials when the verifier is sending transaction_data. so all wallets need to check if transaction_data parameter is in the request and return an error if they do not support it. we might need to clarify this in the definition of invalid_transaction_data error

The Wallet MUST ignore any unrecognized parameters, other than the transaction_data parameter. One exception to this rule is transaction_data parameter, and the wallets that do not support this parameter MUST reject requests that contain it.