[GoRouter] and CupertinoSheetRoute doesn't work correctly together. CupertinoSheetRoute always uses root navigator to pop.

### Steps to reproduce

- Create an app with GoRouter using StatefulShellRoute;
- Push from one of StatefulShellBranche's to CupretinoSheetRoute;
- Try to close pushed route.

### Expected results

Pushed route will be closed without problem.

### Actual results

CupertinoSheetRoute uses root navigator and pops entire stack of pages.

### Code sample

<details open><summary>Code sample</summary>

```dart
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';

void main() {
  runApp(const MyApp());
}

class _CustomPage<T> extends Page<T> {
  final Widget child;

  const _CustomPage(
      {super.key,
      super.name,
      super.arguments,
      super.restorationId,
      super.canPop,
      super.onPopInvoked,
      required this.child});

  @override
  Route<T> createRoute(BuildContext context) => CupertinoSheetRoute<T>(
        settings: this,
        builder: (context) => child,
      );
}

class _ShellBuilder extends StatelessWidget {
  const _ShellBuilder({required this.navigationShell});

  final StatefulNavigationShell navigationShell;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: navigationShell,
      bottomNavigationBar: BottomNavigationBar(
        onTap: (index) => navigationShell.goBranch(index),
        selectedItemColor: Colors.green,
        selectedLabelStyle: TextStyle(color: Colors.green),
        currentIndex: navigationShell.currentIndex,
        items: [
          BottomNavigationBarItem(icon: Icon(Icons.home), label: 'home'),
          BottomNavigationBarItem(icon: Icon(Icons.man), label: 'user'),
        ],
      ),
    );
  }
}

class _HomePage extends StatelessWidget {
  const _HomePage();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Text(
          'home',
          style: TextStyle(color: Colors.black),
        ),
      ),
    );
  }
}

class _UserPage extends StatelessWidget {
  const _UserPage();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: TextButton(
          onPressed: () => context.push('/user/pushedRoute'),
          child: Text(
            'pushToRoute',
            style: TextStyle(color: Colors.black),
          ),
        ),
      ),
    );
  }
}

class _PushedRoute extends StatelessWidget {
  const _PushedRoute();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Text('pushedRoute'),
      ),
    );
  }
}

abstract class _Router {
  static final router = GoRouter(
    debugLogDiagnostics: true,
    initialLocation: '/user',
    routes: [
      StatefulShellRoute.indexedStack(
        branches: [
          StatefulShellBranch(
            routes: [
              GoRoute(
                path: '/home',
                builder: (context, state) => _HomePage(),
              ),
            ],
          ),
          StatefulShellBranch(
            routes: [
              GoRoute(
                path: '/user',
                builder: (context, state) => _UserPage(),
                routes: [
                  GoRoute(
                    path: '/pushedRoute',
                    pageBuilder: (context, state) =>
                        _CustomPage<void>(child: _PushedRoute()),
                  )
                ],
              ),
            ],
          ),
        ],
        builder: (context, state, navigationShell) =>
            _ShellBuilder(navigationShell: navigationShell),
      ),
    ],
  );
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp.router(
      routerConfig: _Router.router,
    );
  }
}

```

</details>


### Screenshots or Video



<details open>
<summary>Screenshots / Video demonstration</summary>
https://github.com/user-attachments/assets/c2d4fc31-30b1-474b-a535-59adf37ec691
</details>


### Logs

<details open><summary>Logs</summary>

```console
[GoRouter] Full paths for routes:
           └─ (ShellRoute)
             ├─/home (_HomePage)
             └─/user (_UserPage)
               └─/user/pushedRoute
[GoRouter] setting initial location /user
2
[GoRouter] Using MaterialApp configuration
[GoRouter] pushing /user/pushedRoute

════════ Exception caught by gesture ═══════════════════════════════════════════
The following assertion was thrown while handling a gesture:
You have popped the last page off of the stack, there are no pages left to show
'package:go_router/src/delegate.dart':
Failed assertion: line 169 pos 7: 'currentConfiguration.isNotEmpty'

When the exception was thrown, this was the stack:
#2      GoRouterDelegate._debugAssertMatchListNotEmpty (package:go_router/src/delegate.dart:169:7)
delegate.dart:169
#3      GoRouterDelegate._completeRouteMatch (package:go_router/src/delegate.dart:190:5)
delegate.dart:190
#4      GoRouterDelegate._handlePopPageWithRouteMatch (package:go_router/src/delegate.dart:148:7)
delegate.dart:148
#5      _CustomNavigatorState._handlePopPage (package:go_router/src/builder.dart:427:42)
builder.dart:427
#6      NavigatorState.pop (package:flutter/src/widgets/navigator.dart:5580:28)
navigator.dart:5580
#7      _CupertinoDownGestureController.dragEnd (package:flutter/src/cupertino/sheet.dart:798:23)
sheet.dart:798
#8      _CupertinoDownGestureDetectorState._handleDragEnd (package:flutter/src/cupertino/sheet.dart:707:29)
sheet.dart:707
#9      DragGestureRecognizer._checkEnd.<anonymous closure> (package:flutter/src/gestures/monodrag.dart:897:47)
monodrag.dart:897
#10     GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:345:24)
recognizer.dart:345
#11     DragGestureRecognizer._checkEnd (package:flutter/src/gestures/monodrag.dart:897:5)
monodrag.dart:897
#12     DragGestureRecognizer.didStopTrackingLastPointer (package:flutter/src/gestures/monodrag.dart:764:9)
monodrag.dart:764
#13     OneSequenceGestureRecognizer.stopTrackingPointer (package:flutter/src/gestures/recognizer.dart:540:9)
recognizer.dart:540
#14     DragGestureRecognizer._giveUpPointer (package:flutter/src/gestures/monodrag.dart:773:5)
monodrag.dart:773
#15     DragGestureRecognizer.handleEvent (package:flutter/src/gestures/monodrag.dart:725:7)
monodrag.dart:725
#16     PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:97:12)
pointer_router.dart:97
#17     PointerRouter._dispatchEventToRoutes.<anonymous closure> (package:flutter/src/gestures/pointer_router.dart:143:9)
pointer_router.dart:143
#18     _LinkedHashMapMixin.forEach (dart:_compact_hash:764:13)
#19     PointerRouter._dispatchEventToRoutes (package:flutter/src/gestures/pointer_router.dart:141:18)
pointer_router.dart:141
#20     PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:131:7)
pointer_router.dart:131
#21     GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:530:19)
binding.dart:530
#22     GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:499:22)
binding.dart:499
#23     RendererBinding.dispatchEvent (package:flutter/src/rendering/binding.dart:473:11)
binding.dart:473
#24     GestureBinding._handlePointerEventImmediately (package:flutter/src/gestures/binding.dart:437:7)
binding.dart:437
#25     GestureBinding.handlePointerEvent (package:flutter/src/gestures/binding.dart:394:5)
binding.dart:394
#26     GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:341:7)
binding.dart:341
#27     GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:308:9)
binding.dart:308
#28     _invoke1 (dart:ui/hooks.dart:347:13)
hooks.dart:347
#29     PlatformDispatcher._dispatchPointerDataPacket (dart:ui/platform_dispatcher.dart:467:7)
platform_dispatcher.dart:467
#30     _dispatchPointerDataPacket (dart:ui/hooks.dart:282:31)
hooks.dart:282
(elided 2 frames from class _AssertionError)

Handler: "onEnd"

```

</details>


### Flutter Doctor output

<details open><summary>Doctor output</summary>

```console
[✓] Flutter (Channel stable, 3.32.6, on macOS 15.3.2 24D81 darwin-arm64, locale en-RU) [314ms]
    • Flutter version 3.32.6 on channel stable at /Users/karimsultanbekov/fvm/versions/3.32.6
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 077b4a4ce1 (3 days ago), 2025-07-08 13:31:08 -0700
    • Engine revision 72f2b18bb0
    • Dart version 3.8.1
    • DevTools version 2.45.1

[✓] Android toolchain - develop for Android devices (Android SDK version 34.0.0) [989ms]
    • Android SDK at /Users/karimsultanbekov/Library/Android/sdk
    • Platform android-35, build-tools 34.0.0
    • Java binary at: /Applications/Android Studio.app/Contents/jbr/Contents/Home/bin/java
      This is the JDK bundled with the latest Android Studio installation on this machine.
      To manually set the JDK path, use: `flutter config --jdk-dir="path/to/jdk"`.
    • Java version OpenJDK Runtime Environment (build 17.0.6+0-17.0.6b829.9-10027231)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 16.4) [576ms]
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 16F6
    • CocoaPods version 1.16.2

[✓] Chrome - develop for the web [64ms]
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2022.3) [63ms]
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 17.0.6+0-17.0.6b829.9-10027231)

[✓] IntelliJ IDEA Ultimate Edition (version 2024.2.3) [62ms]
    • IntelliJ at /Applications/IntelliJ IDEA.app
    • Flutter plugin version 82.1.3
    • Dart plugin version 242.22855.32

[✓] VS Code (version 1.95.3) [6ms]
    • VS Code at /Users/karimsultanbekov/Downloads/Visual Studio Code.app/Contents
    • Flutter extension version 3.114.0

[✓] Network resources [332ms]
    • All expected network resources are available.

• No issues found!
```

</details>


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[GoRouter] and CupertinoSheetRoute doesn't work correctly together. CupertinoSheetRoute always uses root navigator to pop. #172010

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[GoRouter] and CupertinoSheetRoute doesn't work correctly together. CupertinoSheetRoute always uses root navigator to pop. #172010

Description

Steps to reproduce

Expected results

Actual results

Code sample

Screenshots or Video

Logs

Flutter Doctor output

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

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