veri tabanindan yazilari listelemek istedigimde burda (yazi 1 ve yazi 2 satirlarinda hata aliyorum) hata aliyorum bu kodun guncelini nasil bulabilirm

class TumYazilar extends StatelessWidget {
 

  @override
  Widget build(BuildContext context) {
    CollectionReference yazilar =
        FirebaseFirestore.instance.collection('Yazilar');
 
    return StreamBuilder<QuerySnapshot>(
      stream: yazilar.snapshots(),
      builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
        if (snapshot.hasError) {
          return Text('Something went wrong');
        }
 
        if (snapshot.connectionState == ConnectionState.waiting) {
          return Text("Loading");
        }
        
        // ignore: unnecessary_new
        return new ListView(
          children: snapshot.data!.docs.map((DocumentSnapshot document) {
            // ignore: unnecessary_new
            return new ListTile(

              title:  Text(document.data()!['yazi1']), 
              subtitle: Text(document.data()!['yazi2']),
            );
          }).toList(),
        );
      },
      
    );
  }