"Scanning parameters are not set" on Hot Restart

xvrh commented 3 years ago

Describe the bug On Android, I consistently have a failure on the first scanForDevices after a Hot Restart.

To Reproduce Steps to reproduce the behavior:

This program have a single button to start a bluetooth scan

import 'package:flutter/material.dart';
import 'package:flutter_reactive_ble/flutter_reactive_ble.dart';

void main() => runApp(MaterialApp(
      home: Scaffold(
        body: BluetoothApp(),
      ),
    ));

final _client = FlutterReactiveBle();

class BluetoothApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return SafeArea(
      child: RaisedButton(
        onPressed: () {
          _client.scanForDevices(
              withServices: [], scanMode: ScanMode.lowLatency).listen((device) {
            print('Found ${device.name}');
          }, onError: (e) {
            print('Scan error $e');
          }, cancelOnError: true);
        },
        child: Text('Start scan'),
      ),
    );
  }
}

Run the program and press "Start scan"
During the scan, execute a Hot Restart
After the application restart, press "Start scan" again
It fails with Scan error Exception: GenericFailure<ScanFailure>(code: ScanFailure.unknown, message: "Scanning parameters are not set")
Press a second time, it works now.

Expected behavior It would improve developer experience if the library was more resilient to this case.

Smartphone / tablet I can consistently reproduce on this 3 devices: Motorola G5 (Android 8.1.0), Huawei P9 lite (Android 7.0), Nokia android One (Android 9)

Package version: 2.5.0

Peripheral device NA

Additional context This error message has already been reported here: https://github.com/PhilipsHue/flutter_reactive_ble/issues/87 but I don't known if this is the same issue.