Flutter + firebase

image ช่วยแปลcode บรรทัดที่ 30-32 หน่อยครับผมงงว่าผมทำผิดเงื่อนไขยังไง มันถึงแสดงค่า else มา

import 'package:firebase_database/firebase_database.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:google_fonts/google_fonts.dart';

class IotScreen extends StatefulWidget {
  @override
  _IotScreenState createState() => _IotScreenState();
}

class _IotScreenState extends State<IotScreen> {
  bool value = false;
  final dbRef = FirebaseDatabase.instance.reference();

  onUpdate() {
    setState(() {
      value = !value;
    });
  }

  Widget build(BuildContext context) {
    SystemChrome.setPreferredOrientations(
        [DeviceOrientation.portraitDown, DeviceOrientation.portraitUp]);
    return SafeArea(
        child: Scaffold(
      body: StreamBuilder(
          stream: dbRef.child("Data").onValue,
          // ignore: missing_return
          builder: (context, snapshot) {
            if  (snapshot.hasData &&
                !snapshot.hasError &&
                snapshot.data.snapshot.value != null) {
              return Column(children: [
                Padding(
                  padding: EdgeInsets.all(18),
                  child: Row(
                    mainAxisAlignment: MainAxisAlignment.spaceBetween,
                    children: [
                      Icon(
                        Icons.clear_all,
                      ),
                      Text(
                        "My Room",
                        style: GoogleFonts.robotoSlab(
                          fontSize: 20,
                          fontWeight: FontWeight.bold,
                        ),
                      ),
                      Icon(Icons.settings),
                    ],
                  ),
                ),
                SizedBox(
                  height: 20,
                ),
                Column(
                  children: [
                    Text(
                      "Temperature",
                      style: GoogleFonts.robotoSlab(
                        fontSize: 24,
                        fontWeight: FontWeight.bold,
                      ),
                    ),
                    Padding(
                      padding: EdgeInsets.all(8),
                      child: Text(
                        snapshot.data.value["Temperature:"]
                            .toString() +
                            "°C",
                        style: GoogleFonts.robotoSlab(fontSize: 20),
                      ),
                    ),
                  ],
                ),
                SizedBox(
                  height: 70,
                ),
                FloatingActionButton.extended(
                  onPressed: () {
                    onUpdate();
                    writeData();
                  },
                  label: value
                      ? Text("ON",
                          style: GoogleFonts.robotoSlab(
                              fontSize: 18,
                              fontWeight: FontWeight.bold,
                              color: Colors.greenAccent[400]))
                      : Text(
                          "OFF",
                          style: GoogleFonts.robotoSlab(
                              fontSize: 18,
                              fontWeight: FontWeight.bold,
                              color: Colors.red),
                        ),
                  elevation: 20,
                  backgroundColor: Colors.grey[500],
                  icon: value
                      ? Icon(
                          Icons.visibility,
                          color: Colors.yellow,
                        )
                      : Icon(
                          Icons.visibility_off,
                          color: Colors.yellow,
                        ),
                ),
              ]);
            }
            else {
             return Container();
            }
          }),
    ));
  }

  Future<void> writeData() async {
    //dbRef.child("Date").set({"Temperature:": 0});
    dbRef.child("LightState").set({"switch": !value});
  }
}


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