updateSession method Null safety

Implementation

Future<void> updateSession() async {
  // add completion
  sdk.eventManager.notifySessionExpired();

  // If websocket exists, ws request to update session key
  if (sdk.webSocket?.isConnected() == true) {
    try {
      await sdk.cmdManager
          .sendCommand(Command.buildLOGIUpdateSessionKey(_accessToken));
    } catch (e) {
      logger.e('WS LOGI extend session Error: ' + e.toString());
      throw WebSocketError(
          message: 'LOGI extend session error: ' + e.toString());
    } finally {
      return;
    }
  }

  final completer = Completer();
  sessionUpdateCompleters.add(completer);

  if (isRefreshingKey) {
    return completer.future;
  }

  final appId = sdk.state.appId;
  final accessToken = _accessToken;

  if (appId == null || accessToken == null) throw UnauthorizeError();

  final hasSessionHandler = sdk.eventManager.getSessionHandler() != null;

  isRefreshingKey = true;

  logger.i('Updating session with $_accessToken');

  try {
    final res = await sdk.api.send(
      AppSessionKeyUpdateRequest(
        appId: appId,
        accessToken: accessToken,
        expiringSession: hasSessionHandler,
      ),
    );
    isRefreshingKey = false;
    logger.i('Updated session $res');
    _applyRefreshedSessionKey(res);
    return completer.future;
  } on SBError catch (err) {
    logger.w('Failed to update session sb $err');
    isRefreshingKey = false;
    if (err.code == ErrorCode.accessTokenNotValid) {
      sdk.eventManager.notifySessionTokenRequired();
    } else {
      flushResultCompleters(SessionKeyRefreshFailedError());
      sdk.eventManager.notifySessionError(SessionKeyRefreshFailedError());
    }
    return completer.future;
  } catch (err) {
    logger.w('Failed to update session $err');
    isRefreshingKey = false;
    flushResultCompleters(SessionKeyRefreshFailedError());
    sdk.eventManager.notifySessionError(SessionKeyRefreshFailedError());
    return completer.future;
  }
}