不良状态：文档中不存在字段napshotplatform

Question

我遇到了这个错误，这与我的StreamBuilder有关。我还尝试过message.data（）['text']，但这似乎也没有用。

child: Column(
          mainAxisAlignment: MainAxisAlignment.spaceBetween,
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            StreamBuilder<QuerySnapshot>(
                stream: _firestore.collection('messages').snapshots(),
                builder: (BuildContext context,
                    AsyncSnapshot<QuerySnapshot> snapshot) {
                  if (!snapshot.hasData) {
                    return Center(
                      child: CircularProgressIndicator(
                        backgroundColor: Colors.lightBlueAccent,
                      ),
                    );
                  } else if (snapshot.hasData) {
                    final messages = snapshot.data.docs;
                    List<Text> messageWidgets = [];

                    for (var message in messages) {
                      final messageText = message.data['text'];
                      final messageSender = message.data['sender'];

                      final messageWidget =
                          Text('$messageText from $messageSender');
                      messageWidgets.add(messageWidget);
                    }
                    return Column(
                      children: messageWidgets,
                    );
                  }
                }),