Merge pull request #200 from openid/awoie/fix-191

fix: add wallet_unavailable error code; fixes #191

openid-4-verifiable-presentations-1_0.md

@@ -788,6 +788,10 @@ This document also defines the following additional error codes and error descri
 
 - The value of the `request_uri_method` request parameter is neither `get` nor `post` (case-sensitive).
 
+`wallet_unavailable`:
+
+- The Wallet appears to be unavailable and therefore unable to respond to the request. It can be useful in situations where the User Agent cannot invoke the Wallet and another component receives the request while the End-User wishes to continue the journey on the Verifier website. For example, this applies when using claimed HTTPS URIs handled by the Wallet provider in case the platform cannot or does not translate the URI into a platform intent to invoke the Wallet. In this case, the Wallet provider would return the Authorization Error Response to the Verifier and might redirect the User Agent back to the Verifier website.
+
 
 ## VP Token Validation
 
@@ -1202,6 +1206,10 @@ Mandatory user interaction before sending the request, like clicking a button, u
 
 Requests from the Wallet to the Verifier SHOULD be sent with the minimal amount of information possible, and in particular, without any HTTP headers identifying the software used for the request (e.g., HTTP libraries or their versions). The Wallet MUST NOT send PII or any other data that could be used for fingerprinting to the Request URI in order to prevent user tracking. 
 
+## Authorization Error Response with the `wallet_unavailable` error code
+
+In the event that another component is invoked instead of the Wallet, the user MUST be informed and give consent before the invoked component returns the `wallet_unavailable` Authorization Error Response to the Verifier.
+
 {backmatter}
 
 <reference anchor="VC_DATA" target="https://www.w3.org/TR/2022/REC-vc-data-model-20220303/">
@@ -2044,6 +2052,7 @@ The technology described in this specification was made available from contribut
    * added references to ISO/IEC 23220 and 18013 documents 
    * added `post` request method for Request URI
    * Added IETF SD-JWT VC profile
+   * Added `wallet_unavailable` error
 
    -20