Flutter use ProxyProvider

Description

I have a page(InitialElementResultScreen) that has to wait for several operations to be done in the InitialElementResultNotifier to display the rest of the page.

Code that works

My InitialElementResultScreen:

class InitialElementResultScreen extends StatelessWidget {
  final String title;
  InitialElementResultScreen({
    Key key,
    @required this.title,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBarWidget.withoutMenu(title: title),
      body: _buildBody(context),
    );
  }

  Widget _buildBody(BuildContext context){

    // => For use variable in my screen I use the notifier.
    var _initialElementResultProvider = Provider.of<InitialElementResultNotifier>(context);

    return SingleChildScrollView(
      child: Column(
        children: [
          ContainerComponent(
            colorContainer: AppColors.backgroundLightBasic,
            children: [
              FutureBuilder(
                  future: _initialElementResultProvider.myFuture,
                  builder: (context, snapshot){
                    if(!snapshot.hasData) {
                      return Text('loading');
                    }else{
                      return Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: [
                          // ... some widgets
                        ],
                      );
                    }
                  }
              )
            ],
          ),
        ],
      ),
    );
  }
}

When I call my InitialElementResultScreen :

ChangeNotifierProvider<InitialElementResultNotifier>(
    create: (BuildContext context) => InitialElementResultNotifier(getData: data)
)

My InitialElementResultNotifier receives external data directly in its constructor. It converts them to objects so that I can do operations on them.

My InitialElementResultNotifier :

class InitialElementResultNotifier with ChangeNotifier{

  // External Notifier
  // ---------------------------------------------------------------------------

  // Variables
  // ---------------------------------------------------------------------------
  FormInitialElementModel dataReceived;
  Future myFuture;

  // Constructor
  // ---------------------------------------------------------------------------
  InitialElementResultNotifier({
    @required String getData,
  }){
    _initialise(getData);
  }

  // Initialisation
  // ---------------------------------------------------------------------------
  Future _initialise(String getData) async{
    print('--- initialise');

    dataReceived = await _convertDataReceived(getData);
    myFuture = loadingInitialElementData();
  }

  // Functions public
  // ---------------------------------------------------------------------------
  Future<void> loadingInitialElementData() async
  {
    print('---------------------- dataReceived');
    print(dataReceived); // => I see my data in the console
    // ... some operations
  }
}

Code that does not work

In my function which loadingInitialElementData (), I would like to have access to another notifier. The notifier LoaderNotifier manages the display of different messages depending on its state that I will change according to my operations in the loadingInitialElementData() function.

For this I will use a proxy Provider. So now I call my InitialElementResultScreen like that:

ChangeNotifierProvider<LoaderNotifier>(
    create: (BuildContext context) => LoaderNotifier()
),
ProxyProvider<LoaderNotifier, InitialElementResultNotifier>(
    update: (BuildContext context, LoaderNotifier loaderNotifier, InitialElementResultNotifier initialElementResultNotifier) {
      return InitialElementResultNotifier(
          getData: data,
          loaderNotifier: loaderNotifier
      );
    }
),

I will update my InitialElementResultNotifier:

All the code is the same except 3 lines to be able to call on my other Notifier. I marked the lines as comments in the code

class InitialElementResultNotifier with ChangeNotifier{

  // External Notifier
  // ---------------------------------------------------------------------------
  LoaderNotifier _loaderNotifier; // => New line !

  // Variables
  // ---------------------------------------------------------------------------
  FormInitialElementModel dataReceived;
  Future myFuture;

  // Constructor
  // ---------------------------------------------------------------------------
  InitialElementResultNotifier({
    @required String getData,
    LoaderNotifier loaderNotifier, // => New line !
  }){
    _loaderNotifier = loaderNotifier; // => New line !
    _initialise(getData);
  }

  // Initialisation
  // ---------------------------------------------------------------------------
  Future _initialise(String getData) async{
    print('--- initialise');

    dataReceived = await _convertDataReceived(getData);
    myFuture = loadingInitialElementData();
  }

  // Functions public
  // ---------------------------------------------------------------------------
  Future<void> loadingInitialElementData() async
  {
    print('---------------------- dataReceived');
    print(dataReceived); // => I see my data in the console
    // ... some operations
  }
}

Error

I don't understand why I've this error, what is my mistake ?

======== Exception caught by widgets library =======================================================
The following assertion was thrown building InitialElementResultScreen(dirty, dependencies: [_InheritedProviderScope<InitialElementResultNotifier>]):
Tried to use Provider with a subtype of Listenable/Stream (InitialElementResultNotifier).


This is likely a mistake, as Provider will not automatically update dependents
when InitialElementResultNotifier is updated. Instead, consider changing Provider for more specific
implementation that handles the update mechanism, such as:

- ListenableProvider
- ChangeNotifierProvider
- ValueListenableProvider
- StreamProvider

Alternatively, if you are making your own provider, consider using InheritedProvider.

If you think that this is not an error, you can disable this check by setting
Provider.debugCheckInvalidValueType to `null` in your main file: