[go_router] Fix return type of current state getter to be non-nullable (#8173)

The `state` getter returns a `GoRouterState?`, but I don't think it needs to be nullable since `currentConfiguration.last.buildState()` never returns `null`.

I'm not sure if it is nullable on purpose for some changes planned in the Future. If there is a reason, it might be better to add a comment about it. Otherwise, it is just inconvenient that a null check is necessary.

Author: kaboc

packages/go_router/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 14.7.1
+
+- Fixes return type of current state getter on `GoRouter` and `GoRouterDelegate` to be non-nullable.
+
 ## 14.7.0
 
 - Adds fragment support to GoRouter, enabling direct specification and automatic handling of fragments in routes.
@@ -11,7 +15,6 @@
 - Updates minimum supported SDK version to Flutter 3.22/Dart 3.4.
 - Updates readme.
 
-
 ## 14.6.2
 
 - Replaces deprecated collection method usage.

packages/go_router/lib/src/delegate.dart

@@ -182,7 +182,7 @@ class GoRouterDelegate extends RouterDelegate<RouteMatchList>
 
   /// The top [GoRouterState], the state of the route that was
   /// last used in either [GoRouter.go] or [GoRouter.push].
-  GoRouterState? get state => currentConfiguration.last
+  GoRouterState get state => currentConfiguration.last
       .buildState(_configuration, currentConfiguration);
 
   /// For use by the Router architecture as part of the RouterDelegate.

packages/go_router/lib/src/router.dart

@@ -261,7 +261,7 @@ class GoRouter implements RouterConfig<RouteMatchList> {
   /// Accessing this property via GoRouter.of(context).state will not
   /// cause rebuild if the state has changed, consider using
   /// GoRouterState.of(context) instead.
-  GoRouterState? get state => routerDelegate.state;
+  GoRouterState get state => routerDelegate.state;
 
   /// Whether the imperative API affects browser URL bar.
   ///

packages/go_router/pubspec.yaml

@@ -1,8 +1,7 @@
 name: go_router
 description: A declarative router for Flutter based on Navigation 2 supporting
   deep linking, data-driven routes and more
-version: 14.7.0
-
+version: 14.7.1
 repository: https://github.com/flutter/packages/tree/main/packages/go_router
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+go_router%22
 

packages/go_router/test/go_router_test.dart

@@ -6030,39 +6030,39 @@ void main() {
     await tester.pumpAndSettle();
 
     GoRouterState? state = router.state;
-    expect(state?.name, 'home');
-    expect(state?.fullPath, '/');
+    expect(state.name, 'home');
+    expect(state.fullPath, '/');
 
     router.go('/books');
     await tester.pumpAndSettle();
     state = router.state;
-    expect(state?.name, 'books');
-    expect(state?.fullPath, '/books');
+    expect(state.name, 'books');
+    expect(state.fullPath, '/books');
 
     router.push('/boats');
     await tester.pumpAndSettle();
     state = router.state;
-    expect(state?.name, 'boats');
-    expect(state?.fullPath, '/boats');
+    expect(state.name, 'boats');
+    expect(state.fullPath, '/boats');
 
     router.pop();
     await tester.pumpAndSettle();
     state = router.state;
-    expect(state?.name, 'books');
-    expect(state?.fullPath, '/books');
+    expect(state.name, 'books');
+    expect(state.fullPath, '/books');
 
     router.go('/tulips');
     await tester.pumpAndSettle();
     state = router.state;
-    expect(state?.name, 'tulips');
-    expect(state?.fullPath, '/tulips');
+    expect(state.name, 'tulips');
+    expect(state.fullPath, '/tulips');
 
     router.go('/books');
     router.push('/tulips');
     await tester.pumpAndSettle();
     state = router.state;
-    expect(state?.name, 'tulips');
-    expect(state?.fullPath, '/tulips');
+    expect(state.name, 'tulips');
+    expect(state.fullPath, '/tulips');
   });
 
   testWidgets('should allow route paths without leading /',