Merhaba. Flutter firebaseden verileri alt alta listelemek istiyorum ama [core/no-app] No Firebase App '[DEFAULT]' has been created - call Firebase.initializeApp() hatası veriyor.
kodlar aşağıda. yardımcı olursanız sevinirim.

import 'package:flutter/material.dart';

import 'package:firebase_core/firebase_core.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:tarih/sonuc.dart';

void main() {
  runApp(guncelPage());
}

class guncelPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    CollectionReference users = FirebaseFirestore.instance.collection('soru');

    return StreamBuilder<QuerySnapshot>(
      stream: users.snapshots(),
      builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
        if (snapshot.hasError) {
          return Text('Something went wrong');
        }

        if (snapshot.connectionState == ConnectionState.waiting) {
          return Text("Loading");
        }

        return new ListView(
          children: snapshot.data.documents.map((DocumentSnapshot document) {
            return new ListTile(
              title: new Text(document.data()['sorubaslik']),
              subtitle: new Text(document.data()['acevap']),
            );
          }).toList(),
        );
      },
    );
  }
}