How is the Example supposed to work? I get a "type Null is not a subtype of type Future<dynamic>" error about mockingjay HOT 7 CLOSED

onPressed: () => Navigator.of(context).push(MySettingsPage.route()),

onPressed: () => Navigator.of(context).push<void>(MySettingsPage.route()),

static Route route() {
    return MaterialPageRoute(
      builder: (_) => const MySettingsPage(),
      settings: const RouteSettings(name: '/settings'),
    );
}

static Route<void> route() {
    return MaterialPageRoute<void>(
      builder: (_) => const MySettingsPage(),
      settings: const RouteSettings(name: '/settings'),
    );
}

when(() => navigator.push(any())).thenAnswer((_) async {});

when(() => navigator.push<void>(any())).thenAnswer((_) async {});

verify(() => navigator.push(any(that: isRoute<void>(whereName: equals('/settings'))))).called(1);

verify(() => navigator.push<void>(any<Route<void>>(that: isRoute<void>(whereName: equals('/settings'))))).called(1);

The following _TypeError was thrown running a test:
type 'Null' is not a subtype of type 'Future<Object?>'

When the exception was thrown, this was the stack:
#0      MockNavigator.pushNamed (package:flutter/src/widgets/navigator.dart:4094:14)
#1      _MockNavigatorState.pushNamed (package:mockingjay/src/mock_navigator.dart:88:23)

static Route<void> route() {