watchtower/wtwire/error_code: add DeleteSessionCodeNotFound string

watchtower/wtwire/delete_session_reply.go

@@ -12,8 +12,6 @@ const (
 	// client side, or that the tower had already deleted the session in a
 	// prior request that the client may not have received.
 	DeleteSessionCodeNotFound DeleteSessionCode = 80
-
-	// TODO(conner): add String method after wtclient is merged
 )
 
 // DeleteSessionReply is a message sent in response to a client's DeleteSession

watchtower/wtwire/error_code.go

@@ -46,6 +46,8 @@ func (c ErrorCode) String() string {
 		return "StateUpdateCodeMaxUpdatesExceeded"
 	case StateUpdateCodeSeqNumOutOfOrder:
 		return "StateUpdateCodeSeqNumOutOfOrder"
+	case DeleteSessionCodeNotFound:
+		return "DeleteSessionCodeNotFound"
 	default:
 		return fmt.Sprintf("UnknownErrorCode: %d", c)
 	}