Exception ao invocar calcPrecoPrazo

[mon1eiro]

---------------------------------------------------------Classe Calculadora------------------------------------------------------------

import 'package:sigepweb/sigepweb.dart';

class Calculadora {


  final sigepweb = Sigepweb(contrato: SigepContrato.semContrato());

  Future<void> calcFrete() async{
    final calcPrecoPrazo = await sigepweb.calcPrecoPrazo(
      cepOrigem: '01021200',
      cepDestino: '69911470',
      valorPeso: 1,
      formatoEncomenda: FormatoEncomenda.caixa,
      comprimento: 18,
      largura: 13,
      altura: 9
    );

    for (final item in calcPrecoPrazo) {
      print("${item.nome}: R\$ ${item.valor}");
    }
  }
}

----------------------------------------------------------------Método Main-------------------------------------------------------------

import 'package:flutter/material.dart';
import 'package:frete_correios/calculadora.dart';

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

  Calculadora calculadora = Calculadora();

  calculadora.calcFrete();
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Frete Correios'),
        centerTitle: true,
      ),
      body: Container(),
    );
  }
}

------------------------------------------------------------------------Run-----------------------------------------------------------------

Performing hot restart...
Syncing files to device sdk gphone x86...
Restarted application in 4.201ms.

======== Exception caught by widgets library =======================================================
The following assertion was thrown building MyApp:
No MediaQuery widget ancestor found.

Scaffold widgets require a MediaQuery widget ancestor.
The specific widget that could not find a MediaQuery ancestor was: Scaffold
dirty
state: ScaffoldState#912c9(lifecycle state: initialized, tickers: tracking 2 tickers)
The ownership chain for the affected widget is: "Scaffold ← MyApp ← [root]"

No MediaQuery ancestor could be found starting from the context that was passed to MediaQuery.of(). This can happen because you have not added a WidgetsApp, CupertinoApp, or MaterialApp widget (those widgets introduce a MediaQuery), or it can happen if the context you use comes from a widget above those widgets.

The relevant error-causing widget was:
MyApp file:///C:/Users/corre/Desktop/Projetos/frete_correios/lib/main.dart:6:10
When the exception was thrown, this was the stack:
#0 debugCheckHasMediaQuery. (package:flutter/src/widgets/debug.dart:219:7)
#1 debugCheckHasMediaQuery (package:flutter/src/widgets/debug.dart:234:4)
#2 MediaQuery.of (package:flutter/src/widgets/media_query.dart:820:12)
#3 ScaffoldState.didChangeDependencies (package:flutter/src/material/scaffold.dart:2820:50)
#4 StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:4725:11)
...

E/flutter (22460): [ERROR:flutter/lib/ui/ui_dart_state.cc(186)] Unhandled Exception: Erro interno do package. Por favor considere abrir uma questão em https://github.com/marcobraghim/sigepweb/issues
E/flutter (22460): Mensagem da exception foi: DioError [DioErrorType.DEFAULT]: Bad state: Insecure HTTP is not allowed by platform: http://ws.correios.com.br/calculador/CalcPrecoPrazo.asmx/CalcPrecoPrazo?nCdEmpresa=08082650&sDsSenha=564321&nCdServico=04014%2C04510&sCepOrigem=01021200&sCepDestino=69911470&nVlPeso=1.0&nCdFormato=1&nVlComprimento=20&nVlAltura=20&nVlLargura=20&nVlDiametro=0&sCdMaoPropria=N&nVlValorDeclarado=0.0&sCdAvisoRecebimento=N&StrRetorno=xml&nIndicaCalculo=3
E/flutter (22460): #0 _HttpClient._openUrl (dart:_http/http_impl.dart:2434:7)
E/flutter (22460): #1 _HttpClient.openUrl (dart:_http/http_impl.dart:2341:7)
E/flutter (22460): #2 DefaultHttpClientAdapter.fetch (package:dio/src/adapters/io_adapter.dart:35:40)
E/flutter (22460): #3 DioMixin._dispatchRequest (package:dio/src/dio.dart:922:46)
E/flutter (22460):
E/flutter (22460): #4 Future.any.onValue (dart:async/future.dart)
E/flutter (22460):
E/flutter (22460):
E/flutter (22460): #0 Sigepweb.calcPrecoPrazo (package:sigepweb/src/core.dart:166:7)
E/flutter (22460):
E/flutter (22460): #1 Calculadora.calcFrete (package:frete_correios/calculadora.dart:10:28)
E/flutter (22460):
E/flutter (22460):

======== Exception caught by widgets library =======================================================
The following assertion was thrown building MyApp:
No MediaQuery widget ancestor found.

Scaffold widgets require a MediaQuery widget ancestor.
The specific widget that could not find a MediaQuery ancestor was: Scaffold
dirty
state: ScaffoldState#585e0(lifecycle state: initialized, tickers: tracking 2 tickers)
The ownership chain for the affected widget is: "Scaffold ← MyApp ← [root]"

No MediaQuery ancestor could be found starting from the context that was passed to MediaQuery.of(). This can happen because you have not added a WidgetsApp, CupertinoApp, or MaterialApp widget (those widgets introduce a MediaQuery), or it can happen if the context you use comes from a widget above those widgets.

The relevant error-causing widget was:
MyApp file:///C:/Users/corre/Desktop/Projetos/frete_correios/lib/main.dart:6:10
When the exception was thrown, this was the stack:
#0 debugCheckHasMediaQuery. (package:flutter/src/widgets/debug.dart:219:7)
#1 debugCheckHasMediaQuery (package:flutter/src/widgets/debug.dart:234:4)
#2 MediaQuery.of (package:flutter/src/widgets/media_query.dart:820:12)
#3 ScaffoldState.didChangeDependencies (package:flutter/src/material/scaffold.dart:2820:50)
#4 StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:4725:11)
...

[mon1eiro]

Encontrei uma solução para o problema com o http. Adicionando em androidmanifest.xml o seguinte:

<application android:usesCleartextTraffic="true>"

Mas não sei qual seria a implicação no momento da publicação nas lojas...

documentação