The getter 'address' was called on null. Bluetooth connection to a device

[riteshghimire9090]

I am getting error of:
The getter 'address' was called on null. Bluetooth connection to a device

import 'dart:convert';
import 'dart:typed_data';

import 'package:flutter_bluetooth_serial/flutter_bluetooth_serial.dart';

class Obd {
BluetoothConnection connection;
String address;
String _messageBuffer = '';

void initObd(address) {
BluetoothConnection.toAddress(address).then((_connection) {
print('Connected to the device');
connection = _connection;

  connection.input.listen(_onDataReceived).onDone(() {
    print("Is Connected: " + _connection.isConnected.toString());
  });
}).catchError(
  (error) {
    print('Cannot connect, exception occured');
    print(error);
  },
);

}

void _onDataReceived(Uint8List data) {
// Allocate buffer for parsed data

int backspacesCounter = 0;
data.forEach((byte) {
  print(byte);
  if (byte == 8 || byte == 127) {
    backspacesCounter++;
  }
});
Uint8List buffer = Uint8List(data.length - backspacesCounter);
int bufferIndex = buffer.length;

// Apply backspace control character
backspacesCounter = 0;
for (int i = data.length - 1; i >= 0; i--) {
  if (data[i] == 8 || data[i] == 127) {
    backspacesCounter++;
  } else {
    if (backspacesCounter > 0) {
      backspacesCounter--;
    } else {
      buffer[--bufferIndex] = data[i];
    }
  }
}

// Create message if there is new line character
String dataString = String.fromCharCodes(buffer);
int index = buffer.indexOf(13);
if (~index != 0) {
  _messageBuffer = dataString.substring(index);
  print("////////////////////////1");
  print(index);
  print("////////////////////////");
} else {
  _messageBuffer = (backspacesCounter > 0
      ? _messageBuffer.substring(
          0, _messageBuffer.length - backspacesCounter)
      : _messageBuffer + dataString);
  print("////////////////////////2");
  print(_messageBuffer);
  print("////////////////////////");
}

}

void sendMessage(String text) async {
print(text);
text = text.trim();
print(text);

if (text.length > 0) {
  try {
    connection.output.add(utf8.encode("1"));
    await connection.output.allSent;

    print("ll");
  } catch (e) {
    print(e);

    // Ignore error, but notify state

  }
  print("Send Successfully");
}

}
}

[nightscape]

The null-safe branch has just been merged. It still has a few unsafe casts to non-nullable in it, but in principle it should give you a much better idea of what could be null and what can't.
If you use the current master version from Git, you could check if this flags the problematic call.