Error: Getter not found: AppLifecycleState.suspending:

[bartonhammond]

Following instructions of flutter run:

    ** BUILD FAILED **


Xcode's output:
↳

    Compiler message:
    ../../../tools/flutter/.pub-cache/hosted/pub.dartlang.org/graphql_flutter-2.
    0.0/lib/src/widgets/cache_provider.dart:64:30: Error: Getter not found:
    'suspending'.
          case AppLifecycleState.suspending:
                                 ^^^^^^^^^^
    Target kernel_snapshot failed: Exception: Errors during snapshot creation:
    null
    build failed.
    Command PhaseScriptExecution failed with a nonzero exit code
    note: Using new build system
    note: Building targets in parallel
    note: Planning build
    note: Constructing build description

Could not build the application for the simulator.
Error launching application on iPhone SE (2nd generation).