How to use the @orbit/data.NetworkError function in @orbit/data

protected async handleFetchError(e: any): Promise {
    throw new NetworkError(e);
  }
}

let timer = Orbit.globals.setTimeout(() => {
          timedOut = true;
          reject(new NetworkError(`No fetch response within ${timeout}ms.`));
        }, timeout);

this.remote._push = () => {
      this.setupNoError();
      throw new NetworkError('The network is offline.');
    };
  }