I'm using the example code in the doc: https://flutter.io/cookbook/networking/background-parsing/

Unhandled exception:
type 'List' is not a subtype of type 'List' where
[VERBOSE-2:dart_isolate.cc(711)] Isolate (1067271284) 'main.dart:_spawn()' exited with an error
[VERBOSE-2:dart_error.cc(16)] Unhandled exception:
type 'List' is not a subtype of type 'List' where
List is from dart:core
List is from dart:core
Photo is from file:///Users/kwangluu/Workingspace/FlutterProjects/bg_json_parsing/lib/main.dart

#0 parsePhotos (file:///Users/kwangluu/Workingspace/FlutterProjects/bg_json_parsing/lib/main.dart:20:57)
#1 _IsolateConfiguration.apply (package:flutter/src/foundation/isolates.dart:88:16)
#2 _spawn. (package:flutter/src/foundation/isolates.dart:96:30)
#3 Timeline.timeSync (dart:developer/timeline.dart:168:22)
#4 _spawn (package:flutter/src/foundation/isolates.dart:93:12)
#5 _startIsolate. (dart:isolate/runtime/libisolate_patch.dart:282:17)
#6 _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:165:12)

My flutter doctor

[✓] Flutter (Channel master, v0.3.6-pre.24, on Mac OS X 10.13.4 17E202, locale en-VN)
[✓] Android toolchain - develop for Android devices (Android SDK 27.0.3)
[✓] iOS toolchain - develop for iOS devices (Xcode 9.3)
[✓] Android Studio (version 3.1)
[✓] VS Code (version 1.22.2)
[✓] Connected devices (1 available)