gistfile1.txt

///Базовый класс для обработки ошибок, связанных с сервисным слоем
abstract class NetworkErrorHandler implements ErrorHandler {
  @override
  void handleError(Object error) {
    Object e;
    bool isSilent = false;
    bool isOverlayed = false;

    if (error is SilentException) {
      e = error.originalError;
      isSilent = true;
    } else if (error is OverlayedException) {
      e = error.originalError;
      isOverlayed = true;
    } else {
      e = error;
    }

    if (e is Error) {
      e = Exception((e as Error).stackTrace);
    }
    Logger.d("NetworkErrorHandler handle error", e);
    if (e is ConversionException) {
      handleConversionError(
        e,
        isSilent,
        isOverlayed,
      );
    } else if (e is NoInternetException) {
      handleNoInternetError(
        e,
        isSilent,
        isOverlayed,
      );
    } else if (e is HttpProtocolException) {
      handleHttpProtocolException(
        e,
        isSilent,
        isOverlayed,
      );
    } else {
      handleOtherError(
        e,
        isSilent,
        isOverlayed,
      );
    }
  }

  void handleConversionError(
    ConversionException e,
    bool isSilent,
    bool isOverlayed,
  );

  void handleNoInternetError(
    NoInternetException e,
    bool isSilent,
    bool isOverlayed,
  );

  void handleHttpProtocolException(
    HttpProtocolException e,
    bool isSilent,
    bool isOverlayed,
  );

  void handleOtherError(
    Exception e,
    bool isSilent,
    bool isOverlayed,
  );
}

gistfile2.txt

/// Стандартная реализация эррор хендлера
class StandardErrorHandler extends NetworkErrorHandler {
  final MaterialMessageController _messageController;
  final DialogController _dialogController;
  final SessionInteractor _sessionChangedInteractor;

  //ignore: unused_field
  final AuthInteractor _authInteractor;

  StandardErrorHandler(
    this._messageController,
    this._dialogController,
    this._sessionChangedInteractor,
    this._authInteractor,
  );

  @override
  void handleOtherError(
    Exception e,
    bool isSilent,
    bool isOverlayed,
  ) {
    if (e is UserNotFoundException) {
      _dialogController.showAlertDialog(
        message: getStrings().userNotFoundText,
        onAgreeClicked: (_) async {
          _sessionChangedInteractor?.onLogout();
        },
      );
    } else if (e is OtpException) {
      Logger.d("DEV_ERROR $e");
    } else if (e is MessagedException) {
      _show(e.message, isOverlayed);
    } else if (e is InvalidSessionException) {
      _sessionChangedInteractor.onLogout();
    } else {
      if (!isSilent) _show(getStrings().commonErrorText, isOverlayed);
    }
  }

  @override
  void handleHttpProtocolException(
    HttpProtocolException e,
    bool isSilent,
    bool isOverlayed,
  ) {
    if (e is ServerHttpException) {
      if (!isSilent) _show(getStrings().serverErrorMessage, isOverlayed);
    } else if (e is ClientHttpException) {
      _handleClientHttpException(e, isSilent, isOverlayed);
    }
  }

  @override
  void handleConversionError(
    ConversionException e,
    bool isSilent,
    bool isOverlayed,
  ) {
    if (!isSilent) _show(getStrings().badResponseErrorMessage, isOverlayed);
  }

  @override
  void handleNoInternetError(
    NoInternetException e,
    bool isSilent,
    bool isOverlayed,
  ) {
    if (!isSilent) _show(getStrings().noInternetConnectionErrorMessage, isOverlayed);
  }

  void _handleClientHttpException(
    ClientHttpException e,
    bool isSilent,
    bool isOverlayed,
  ) {
    final statusCode = e.response.statusCode;
    if (statusCode == HttpCodes.code403) {
      if (!isSilent) _show(getStrings().forbiddenErrorMessage, isOverlayed);
    } else if (statusCode == HttpCodes.code404) {
      if (!isSilent) _show(getStrings().serverErrorMessage, isOverlayed);
    } else {
      if (!isSilent) _show(getStrings().defaultHttpErrorMessage, isOverlayed);
    }
  }

  void _show(
    String msg,
    bool isOverlayed,
  ) {
    if (!isOverlayed) {
      _messageController.show(
        msg: msg,
        msgType: MsgType
            .commonError, //todo выделить base модуль для всех в стандарте
      );
    } else {
      _messageController.showOverlaySnackbar(msg);
    }
  }
}