fix(op): check if getTokenIDAndClaims succeeded (#429)

When getTokenIDAndClaims didn't succeed,
so `ok` would be false.
This was ignored and the accessTokenClaims.Claims call would panic.

pkg/op/token_exchange.go

@@ -282,6 +282,9 @@ func GetTokenIDAndSubjectFromToken(
 	case oidc.AccessTokenType:
 		var accessTokenClaims *oidc.AccessTokenClaims
 		tokenIDOrToken, subject, accessTokenClaims, ok = getTokenIDAndClaims(ctx, exchanger, token)
+		if !ok {
+			break
+		}
 		claims = accessTokenClaims.Claims
 	case oidc.RefreshTokenType:
 		refreshTokenRequest, err := exchanger.Storage().TokenRequestByRefreshToken(ctx, token)