Fix widget inspector null check (#120143)

* add failing test

* fix

* remove extra whitespace

* fix test failure

* disable trackrebuilddirtywidgets in teardown

* remove no-shuffle annotation

* fix

Author: christopherfujino

packages/flutter/lib/src/widgets/widget_inspector.dart

@@ -2455,7 +2455,10 @@ class _ElementLocationStatsTracker {
       return;
     }
     final _HasCreationLocation creationLocationSource = widget;
-    final _Location location = creationLocationSource._location;
+    final _Location? location = creationLocationSource._location;
+    if (location == null) {
+      return;
+    }
     final int id = _toLocationId(location);
 
     _LocationCount entry;
@@ -3279,7 +3282,7 @@ const TextStyle _messageStyle = TextStyle(
 /// {@macro flutter.widgets.WidgetInspectorService.getChildrenSummaryTree}
 // ignore: unused_element
 abstract class _HasCreationLocation {
-  _Location get _location;
+  _Location? get _location;
 }
 
 /// A tuple with file, line, and column number, for displaying human-readable

packages/flutter/test/widgets/widget_inspector_test.dart

@@ -10,7 +10,7 @@
 // reduced-test-set:
 //   This file is run as part of a reduced test set in CI on Mac and Windows
 //   machines.
-@Tags(<String>['reduced-test-set', 'no-shuffle'])
+@Tags(<String>['reduced-test-set'])
 @TestOn('!chrome')
 library;
 
@@ -220,6 +220,14 @@ class RepaintBoundaryWithDebugPaint extends RepaintBoundary {
   }
 }
 
+Widget _applyConstructor(Widget Function() constructor) => constructor();
+
+class _TrivialWidget extends StatelessWidget {
+  const _TrivialWidget() : super(key: const Key('singleton'));
+  @override
+  Widget build(BuildContext context) => const Text('Hello, world!');
+}
+
 int getChildLayerCount(OffsetLayer layer) {
   Layer? child = layer.firstChild;
   int count = 0;
@@ -240,8 +248,15 @@ class _TestWidgetInspectorService extends TestWidgetInspectorService {
     final TestWidgetInspectorService service = TestWidgetInspectorService();
     WidgetInspectorService.instance = service;
 
-    tearDown(() {
+    tearDown(() async {
       service.resetAllState();
+
+      if (WidgetInspectorService.instance.isWidgetCreationTracked()) {
+        await service.testBoolExtension(
+          WidgetInspectorServiceExtensions.trackRebuildDirtyWidgets.name,
+          <String, String>{'enabled': 'false'},
+        );
+      }
     });
 
     testWidgets('WidgetInspector smoke test', (WidgetTester tester) async {
@@ -3586,6 +3601,28 @@ class _TestWidgetInspectorService extends TestWidgetInspectorService {
       skip: !WidgetInspectorService.instance.isWidgetCreationTracked(), // [intended] Test requires --track-widget-creation flag.
     );
 
+    testWidgets('ext.flutter.inspector.trackRebuildDirtyWidgets with tear-offs', (WidgetTester tester) async {
+      final Widget widget = Directionality(
+        textDirection: TextDirection.ltr,
+        child: WidgetInspector(
+          selectButtonBuilder: null,
+          child: _applyConstructor(_TrivialWidget.new),
+        ),
+      );
+
+      expect(
+        await service.testBoolExtension(
+          WidgetInspectorServiceExtensions.trackRebuildDirtyWidgets.name,
+          <String, String>{'enabled': 'true'},
+        ),
+        equals('true'),
+      );
+
+      await tester.pumpWidget(widget);
+    },
+      skip: !WidgetInspectorService.instance.isWidgetCreationTracked(), // [intended] Test requires --track-widget-creation flag.
+    );
+
     testWidgets('ext.flutter.inspector.trackRebuildDirtyWidgets', (WidgetTester tester) async {
       service.rebuildCount = 0;