Flutter blue plus 库，当try 从 esp32 驱动程序获取 PlatformException 时读取特性

在这里，我试图从esp32驱动程序中读取一个特征，我得到了这些问题. "如果之前调用了ReadCharacteristic，则可能会发生PlatformException(READ_CHARACTIVE_ERROR，未知原因 上次读取完成，NULL，NULL)". 下面我附上了用于读取特征的代码.

 Future<void> readData async{
  BluetoothService? DataService =
  BLEComm().getService(DeviceServiceUUIDs.Service);
  if (null != DataService) {
  await Future.delayed(Duration(milliseconds:50),() async{
  BluetoothCharacteristic? DurationCharacteristic =
  BLEComm().getCharacteristic(
  DeviceServiceUUIDs.duration,
  DataService);
  List<int>? DurationResponse = await BLEComm()
      .readCharacteristic(DurationCharacteristic);
  String Duration = String.fromCharCodes(DurationResponse!);
  var Duration_Data = double.parse(Duration);
  });

在这里，我列出了我习惯于从上面的代码中读取特征的低级函数.

/// Get a specific service from the list of services.
  BluetoothService? getService(String uuid) {
    for (BluetoothService? service in _deviceServices) {
      if (service?.uuid.toString() == uuid) {
        return service;
      }
    }
    return null;
  }


 /// Get Characteristic object from a service
  BluetoothCharacteristic? getCharacteristic(
      String uuid, BluetoothService bleService) {
    var characteristics = bleService.characteristics;
    for (BluetoothCharacteristic characteristic in characteristics) {
      if (characteristic.uuid.toString() == uuid) {
        return characteristic;
      }
    }
    return null;
  }

  /// read value to a characteristic
  /// Throws Exceptions on Non readable characteristic and general exceptions.
  Future<List<int>?> readCharacteristic(
      BluetoothCharacteristic? characteristic) async {
    List<int>? value;
    try {
      if (null != characteristic && !characteristic.properties.read) {
        throw ("characteristic ${characteristic.uuid.toString()} is not readable");
      }
      value = await characteristic?.read();
    } catch (ex) {
      throw Exception(ex);
    }
    return value;
  }
}