chore: update request state, not replace it

Author: sanderPostma

packages/siop-oid4vp/lib/rp/InMemoryRPSessionManager.ts

@@ -207,7 +207,11 @@ export class InMemoryRPSessionManager implements IRPSessionManager {
       }
       let state: AuthorizationRequestState | AuthorizationResponseState
       if (type === 'request') {
-        state = eventState as AuthorizationRequestState
+        const prevState = this.authorizationRequests[event.correlationId]
+        state = {
+          ...prevState,
+          ...eventState
+        } as AuthorizationRequestState
         this.authorizationRequests[event.correlationId] = state
         this.updateMapping(this.nonceMapping, event, 'nonce', event.correlationId, true)
         this.updateMapping(this.stateMapping, event, 'state', event.correlationId, true)