我看不出我在下面做错了什么，但它抛出了一些provider错误和buildcontext：发生这种情况是因为您使用的BuildContext不包含您选择的提供程序。有几种常见的情况：

• 您在main.dart中添加了新的提供程序并执行了热重新加载。要修复此问题，请执行热重启。
• 您尝试读取的提供程序位于不同的路由中。

供应商是“范围”。因此，如果您在路由中插入提供者，则其他路由将无法访问该提供者。

• 您使用了BuildContext，它是您试图读取的提供程序的祖先。

确保SubscriptionsPage位于MultiProvider/Provider下。这通常发生在创建提供程序并试图立即读取它时。
例如，而不是：

Widget build(BuildContext context) {
  return Provider<Example>(
    create: (_) => Example(),
    // Will throw a ProviderNotFoundError, because `context` is associated
    // to the widget that is the parent of `Provider<Example>`
    child: Text(context.watch<Example>()),
  ),
}

考虑使用builder如下：

Widget build(BuildContext context) {
  return Provider<Example>(
    create: (_) => Example(),
    // we use `builder` to obtain a new `BuildContext` that has access to the provider
    builder: (context) {
      // No longer throws
      return Text(context.watch<Example>()),
    }
  ),
}

class RevenueCatProvider extends ChangeNotifier{
          RevenueCatProvider() {
            init();
          }
          Entitlement _entitlement = Entitlement.free;
          Entitlement get entitlement => _entitlement;
          Future init() async {
            Purchases.addPurchaserInfoUpdateListener((purchaserInfo) async {
              updatePurchasesStatus();
            });
          }
          Future updatePurchasesStatus() async {
            final purchaserInfo = await Purchases.getPurchaserInfo();
            final entitlements = purchaserInfo.entitlements.active.values.toList();
            _entitlement = entitlements.isEmpty ? Entitlement.free : Entitlement.pro;
            notifyListeners();
          }
        }

class SubscriptionsPage extends StatefulWidget {
  const SubscriptionsPage({Key? key}) : super(key: key);

  @override
  State<SubscriptionsPage> createState() => _SubscriptionsPageState();
}

class _SubscriptionsPageState extends State<SubscriptionsPage> {
  bool isLoading = false;

  @override
  Widget build(BuildContext context) {

    final entitlement = Provider.of<RevenueCatProvider>(context).entitlement;

   return Scaffold(
      appBar: AppBar(
        title: const Text('Subscription Page'),
      ),
      body: Container(
        alignment: Alignment.center,
        padding: const EdgeInsets.all(32),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            buildEntitlement(entitlement),
            const SizedBox(height: 32),
            Padding(
              padding: const EdgeInsets.only(left: 20.0, right: 20),
              child: ElevatedButton(
                style: ElevatedButton.styleFrom(
                  minimumSize: const Size.fromHeight(50),
                ),
                child: const Text(
                  'See Available Plans',
                  style: TextStyle(fontSize: 20),
                ),
                onPressed: () => isLoading ? null : fetchOffers,
              ),
            ),
            const SizedBox(height: 32),
            SizedBox(
              height: 200,
              child: Image.asset('images/logo_transparent.png'),
            ),
          ],
        ),
      ),
    );
  }

  Widget buildEntitlement(Entitlement entitlement) {

    switch (entitlement) {
      case Entitlement.pro:
        return Column(
          mainAxisAlignment: MainAxisAlignment.end,
          crossAxisAlignment: CrossAxisAlignment.center,
          children: const [
            SizedBox(height: 40),
            Text('You are on a Paid plan',
              style: TextStyle(
                fontSize: 20,
              ),
            ),
            SizedBox(height: 10),
            Icon(Icons.paid,
              size: 100,
            ),
          ],
        );
      case Entitlement.free:
      default:
        return Column(
          mainAxisAlignment: MainAxisAlignment.end,
          crossAxisAlignment: CrossAxisAlignment.center,
          children: const [
            SizedBox(height: 40),
            Text('You are on a Free plan',
              style: TextStyle(
                fontSize: 20,
              ),
            ),
            SizedBox(height: 10),
            Icon(Icons.lock,
              size: 100,
            ),
          ],
        );
    }
  }

  Future fetchOffers() async {
    final offerings = await PurchaseApi.fetchOffers();

    if (offerings.isEmpty) {
      ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
        content: Text('No Subscription'),
      ));
    } else {
      final packages = offerings
          .map((offer) => offer.availablePackages)
          .expand((pair) => pair)
          .toList();

       showModalBottomSheet(
        useRootNavigator: true,
        isDismissible: true,
        isScrollControlled: true,
        backgroundColor: kLightPrimary,
        shape: const RoundedRectangleBorder(
          borderRadius: BorderRadius.vertical(top: Radius.circular(25.0)),
        ),
        context: context,
        builder: (BuildContext context) {
          return StatefulBuilder(
              builder: (BuildContext context, StateSetter setModalState) {
                return PaywallWidget(
                  packages: packages,
                  title: '⭐️ Upgrade your plan',
                  description: 'Upgrade your plan to enjoy unlimited ad-free reviews',
                  onClickedPackage: (package) async {
                    await PurchaseApi.purchasePackage(package);
                    Navigator.pop(context);
                  },
                );
              });
        },
      );
    }
  }
}