message: server: fix error messages.
diff: @@ -543,7 +543,7 @@ func (s *Server) handleTokenRevocation(w http.ResponseWriter, r *http.Request) {
  userID, err := extractUserIdFromCookie(s.Auther, r)
  if err != nil {
  - sendResponse(w, http.StatusBadRequest, apiError{fmt.Sprintf("Failed to revoke refresh token: %v", err)})
  + sendResponse(w, http.StatusBadRequest, apiError{fmt.Sprintf("Failed to revoke refresh token: cannot extract user id from cookie: %v", err)})
  return
  }
  @@ -578,7 +578,7 @@ func (s *Server) handleListClients(w http.ResponseWriter, r *http.Request) {
  userID, err := extractUserIdFromCookie(s.Auther, r)
  if err != nil {
  - sendResponse(w, http.StatusBadRequest, apiError{fmt.Sprintf("Failed to revoke refresh token: %v", err)})
  + sendResponse(w, http.StatusBadRequest, apiError{fmt.Sprintf("Failed to List Client: cannot extract user id from cookie: %v", err)})
  return
  }
  