printerManager.startScan() Errors after 0.4.0 update

[jobypthomas]

@andrey-ushakov @RangerOfGondor
After migrating to Version 0.4.0, when running scan() command, I am getting the following error (with the example code in the repo):

E/flutter ( 9214): [ERROR:flutter/lib/ui/ui_dart_state.cc(209)] Unhandled Exception: type 'Null' is not a subtype of type 'bool' in type cast
E/flutter ( 9214): #0      _$BluetoothDeviceFromJson
package:flutter_bluetooth_basic/src/bluetooth_device.g.dart:14
E/flutter ( 9214): #1      new BluetoothDevice.fromJson
package:flutter_bluetooth_basic/src/bluetooth_device.dart:15
E/flutter ( 9214): #2      BluetoothManager.scan.<anonymous closure>
package:flutter_bluetooth_basic/src/bluetooth_manager.dart:94
E/flutter ( 9214): #3      _MapStream._handleData (dart:async/stream_pipe.dart:213:31)
E/flutter ( 9214): #4      _ForwardingStreamSubscription._handleData (dart:async/stream_pipe.dart:153:13)
E/flutter ( 9214): #5      _rootRunUnary (dart:async/zone.dart:1436:47)
E/flutter ( 9214): #6      _CustomZone.runUnary (dart:async/zone.dart:1335:19)
E/flutter ( 9214): #7      _CustomZone.runUnaryGuarded (dart:async/zone.dart:1244:7)
E/flutter ( 9214): #8      _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:341:11)
E/flutter ( 9214): #9      _BufferingStreamSubscription._add (dart:async/stream_impl.dart:271:7)
E/flutter ( 9214): #10     _SyncBroadcastStreamController._sendData (dart:async/broadcast_stream_controller.dart:378:25)
E/flutter ( 9214): #11     _BroadcastStreamController.add (dart:async/broadcast_stream_controller.dart:244:5)
E/flutter ( 9214): #12     _DoStreamSink.add
package:rxdart/…/transformers/do.dart:40
E/flutter ( 9214): #13     forwardStream.<anonymous closure>.<anonymous closure>.<anonymous closure>
package:rxdart/…/utils/forwarding_stream.dart:31
E/flutter ( 9214): #14     forwardStream.runCatching
package:rxdart/…/utils/forwarding_stream.dart:21
E/flutter ( 9214): #15     forwardStream.<anonymous closure>.<anonymous closure>
package:rxdart/…/utils/forwarding_stream.dart:31
E/flutter ( 9214): #16     _rootRunUnary (dart:async/zone.dart:1436:47)
E/flutter ( 9214): #17     _CustomZone.runUnary (dart:async/zone.dart:1335:19)
E/flutter ( 9214): #18     _CustomZone.runUnaryGuarded (dart:async/zone.dart:1244:7)
E/flutter ( 9214): #19     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:341:11)
E/flutter ( 9214): #20     _BufferingStreamSubscription._add (dart:async/stream_impl.dart:271:7)
E/flutter ( 9214): #21     _SyncBroadcastStreamController._sendData (dart:async/broadcast_stream_controller.dart:378:25)
E/flutter ( 9214): #22     _BroadcastStreamController.add (dart:async/broadcast_stream_controller.dart:244:5)
E/flutter ( 9214): #23     _TakeUntilStreamSink.add
package:rxdart/…/transformers/take_until.dart:13
E/flutter ( 9214): #24     forwardStream.<anonymous closure>.<anonymous closure>.<anonymous closure>
package:rxdart/…/utils/forwarding_stream.dart:31
E/flutter ( 9214): #25     forwardStream.runCatching
package:rxdart/…/utils/forwarding_stream.dart:21
E/flutter ( 9214): #26     forwardStream.<anonymous closure>.<anonymous closure>
package:rxdart/…/utils/forwarding_stream.dart:31
E/flutter ( 9214): #27     _rootRunUnary (dart:async/zone.dart:1436:47)
E/flutter ( 9214): #28     _CustomZone.runUnary (dart:async/zone.dart:1335:19)
E/flutter ( 9214): #29     _CustomZone.runUnaryGuarded (dart:async/zone.dart:1244:7)
E/flutter ( 9214): #30     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:341:11)
E/flutter ( 9214): #31     _BufferingStreamSubscription._add (dart:async/stream_impl.dart:271:7)
E/flutter ( 9214): #32     _ForwardingStreamSubscription._add (dart:async/stream_pipe.dart:123:11)
E/flutter ( 9214): #33     _MapStream._handleData (dart:async/stream_pipe.dart:218:10)
E/flutter ( 9214): #34     _ForwardingStreamSubscription._handleData (dart:async/stream_pipe.dart:153:13)
E/flutter ( 9214): #35     _rootRunUnary (dart:async/zone.dart:1436:47)
E/flutter ( 9214): #36     _CustomZone.runUnary (dart:async/zone.dart:1335:19)
E/flutter ( 9214): #37     _CustomZone.runUnaryGuarded (dart:async/zone.dart:1244:7)
E/flutter ( 9214): #38     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:341:11)
E/flutter ( 9214): #39     _BufferingStreamSubscription._add (dart:async/stream_impl.dart:271:7)
E/flutter ( 9214): #40     _ForwardingStreamSubscription._add (dart:async/stream_pipe.dart:123:11)
E/flutter ( 9214): #41     _WhereStream._handleData (dart:async/stream_pipe.dart:195:12)
E/flutter ( 9214): #42     _ForwardingStreamSubscription._handleData (dart:async/stream_pipe.dart:153:13)
E/flutter ( 9214): #43     _rootRunUnary (dart:async/zone.dart:1436:47)
E/flutter ( 9214): #44     _CustomZone.runUnary (dart:async/zone.dart:1335:19)
E/flutter ( 9214): #45     _CustomZone.runUnaryGuarded (dart:async/zone.dart:1244:7)
E/flutter ( 9214): #46     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:341:11)
E/flutter ( 9214): #47     _DelayedData.perform (dart:async/stream_impl.dart:591:14)
E/flutter ( 9214): #48     _StreamImplEvents.handleNext (dart:async/stream_impl.dart:706:11)
#49     _PendingEvents.schedule.<anonymous closure> (dart:async/stream_impl.dart:663:7)
#50     _rootRun (dart:async/zone.dart:1420:47)
#51     _CustomZone.run (dart:async/zone.dart:1328:19)
#52     _CustomZone.runGuarded (dart:async/zone.dart:1236:7)
#53     _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:1276:23)
#54     _rootRun (dart:async/zone.dart:1428:13)
#55     _CustomZone.run (dart:async/zone.dart:1328:19)
#56     _CustomZone.runGuarded (dart:async/zone.dart:1236:7)
#57     _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:1276:23)
#58     _microtaskLoop (dart:async/schedule_microtask.dart:40:21)
#59     _startMicrotaskLoop (dart:async/schedule_microtask.dart:49:5)
3
find device -> Printer001
find device -> N0A78
5
find device -> Printer001

[jobypthomas]

@andrey-ushakov I tried with iOS and Android both the same behavior. However I see that it found the devices (Printer001 and N0A78, see above ) after the exception.

[jobypthomas]

@andrey-ushakov The error is raised at the dependency - https://pub.dev/packages/flutter_bluetooth_basic
The function "_$BluetoothDeviceFromJson" in "bluetooth_device.dart" json['connected'] is returning null which the program is casted to bool raising the error.

[manimathma]

I am facing the same issue :(

[jobypthomas]

@andrey-ushakov Any update on the fix?

[andrey-ushakov]

A PR was accepted, it should solve the issue.
As I don't have a pos printer currently, it becomes hard to test and maintain the package.
Your PRs are always welcome!! :)

Don't hesitate to reopen the issue if need.

[jobypthomas]

@andrey-ushakov would you update the dependencies (flutter_bluetooth_basic fixed version?) and release the new version of esc_pos_bluetooth?

[andrey-ushakov]

Both packages, flutter_bluetooth_basic and esc_pos_bluetooth were published to pub.dev.
Thank you @jobypthomas for your valuable comments!