lineMatch assertion error in Flutter integration tests - flutter

Question

I'm encountering the following error often, though it's inconsistent and I can't figure out why. I'm using tester as instructed for Flutter Integration tests.
Test Code:
testWidgets('should create and save simulation', (tester) async {
await startApp(tester, app);
await login(tester);
await navigateTo(NavPage.SIMULATOR, tester);
String scenarioName = "CreateAndSaveScenario";
await createScenario(scenarioName, tester);
expect(find.text("CRQ Simulator"), findsWidgets);
expect(find.text("Edit Scenario"), findsWidgets);
expect(find.text(scenarioName), findsWidgets);
Finder fairSwitchFinder = find.byType(Switch);
tester.tap(fairSwitchFinder);
await navigateTo(NavPage.SIMULATOR, tester);
expect(find.byType(ListTile), findsOneWidget);
expect(find.text(scenarioName), findsOneWidget);
});
Error:
══╡ EXCEPTION CAUGHT BY FLUTTER TEST FRAMEWORK ╞═════════════════
The following assertion was thrown running a test:
Assertion failed:
file:///C:/Users/jared/dev/flutter/packages/flutter_test/lib/src/test_async_utils.dart:315:14
lineMatch != null
is not true
When the exception was thrown, this was the stack:
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 266:49 throw_
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 29:3 assertFailed
packages/flutter_test/src/test_async_utils.dart 315:23 _findResponsibleMethod
packages/flutter_test/src/test_async_utils.dart 198:42 guardSync
packages/flutter_test/src/widget_tester.dart 459:18 expect$
views/simulator/crq_simulator_test.dart 37:7 <fn>
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 45:50 <fn>
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/zone.dart 1399:47 _rootRunUnary
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/zone.dart 1300:19 runUnary
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/future_impl.dart 147:18 handleValue
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/future_impl.dart 766:44 handleValueCallback
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/future_impl.dart 795:13 _propagateToListeners
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/future_impl.dart 566:5 [_completeWithValue]
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/future_impl.dart 639:7 <fn>
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/zone.dart 1391:13 _rootRun
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/zone.dart 1293:19 run
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/zone.dart 1201:7 runGuarded
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/zone.dart 1241:23 callback
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/schedule_microtask.dart 40:11 _microtaskLoop
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/schedule_microtask.dart 49:5 _startMicrotaskLoop
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 166:15 <fn>
The test description was:
should create and save simulation
═════════════════════════════════════════════════════════════════
end of failure 1
I was expecting the tester to navigate, but after the fairSwitchFinder tap, it seems to not be able to do anything because the lineMatch is null? The error is not very descriptive

Answer 1

Okay, I figured this out fairly quickly afterward. Surprised there weren't any answers up, but hopefully this question shows up in searches now.
I was missing an await.
I changed
tester.tap(fairSwitchFinder); to await tester.tap(fairSwitchFinder); and it fixed it.