How to resolve null check operator of a variable within a builder?

I'm doing a function statement of QR Code Scanner. When it's not facing the QR Code, it should be in waiting state in else if statement.

else if (result == null) {
  return Column(
   children: [ const Text("Welcome!"), Text("Fee:${load["Fee"]}"), ],
  );
 } 

The problem here is the statement late Message data = Message.fromJson(jsonDecode((result!.code!))); works well if there is no FutureBuilder. But with that, it shows an Exception, Null check operator used on a null value, pointing at the statement of a variable strangely enough.

How can I resolve that? I want to display in waiting state by an else if statement.

Barcode? result;
FutureBuilder<DocumentSnapshot>(
  future: FirebaseFirestore.instance
      .collection('Drivers')
      .doc(FirebaseAuth.instance.currentUser?.email)
      .get(),
  builder: (BuildContext context, AsyncSnapshot<DocumentSnapshot> snapshot) {
    if (snapshot.hasError) { return Text("Something went wrong"); }
    if (snapshot.hasData && !snapshot.data!.exists) { return Text("Document does not exist"); }
    if (snapshot.connectionState == ConnectionState.done) {
      Map<String, dynamic> load = snapshot.data!.data() as Map<String, dynamic>;

          late Message data = Message.fromJson(jsonDecode((result!.code!))); //Null check Operator Runtime Error unless no Builder there.
         int total = data.price * data.passenger;
      return Column(
        children: [
          Row(children: [Text(load["name"]),],),
          //<--- Builder Here
          Container(
            height: 100,
            child: Row(
              mainAxisAlignment:
                  MainAxisAlignment.spaceEvenly,
              children: [
                //FutureBuilder<DocumentSnapshot>(), Needs to access Passenger List. &&(load["Fee"] == data.price)
                Container(child: LayoutBuilder(builder: (context, constraints) {
                  if ((result != null) && (load["Fee"] == data.price)) {
                    return FutureBuilder<DocumentSnapshot>(
                      future: FirebaseFirestore.instance.collection('Users').doc(data.email).get(),
                      builder:(context, snapshot) {
                        if ((snapshot.hasError)||(snapshot.hasData && !snapshot.data!.exists)) { return const Text("Something went wrong, Try again"); }
                        if (snapshot.connectionState == ConnectionState.done) {
                          Map<String, dynamic> moneycheck = snapshot.data!.data() as Map<String, dynamic>;

                          if (moneycheck['Balance'] >= total){
                            //addPayRowUser(data.email, data.totalprice);
                            return Column(
                              children: [
                                Text("Payment Made! \n ${DateTime.now().toString()}"),
                                Text("Price: RM${data.price} per Person"),
                                Text("Total: RM${data.totalprice}"),
                                Text("Persons: ${data.passenger}"),
                              ],
                            );
                          }
                          else if (moneycheck['Balance'] < total){ return 
                          Column( children: [ Text("Insufficient Balance"),
                                Text("Balance: RM ${moneycheck['Balance']}"),Text("Price: RM${data.price} per Person"),
                                 Text("Total: RM${data.totalprice}"),Text("Persons: ${data.passenger}"),
                              ],
                            );
                           }
                        }
                        return const Text("Loading...");
                      },
                    );
                  } 
                  else if (result == null) {
                    return Column(
                      children: [ const Text("Welcome!"), Text("Fee:${load["Fee"]}"), ],
                    );
                  } 
                  else if ((result != null) && (load["Fee"] != data.price)) 
                  {
                    return Column(
                      children: [ const Text("Invalid QR Code!"), Text("${data.price}"), Text("${data.totalprice}"),],
                    );
                  } 
                  else {
                    return const Column(
                      children: [
                        Text("Unknown Error Occured"),
                      ],
                    );
                  }
                })
                    //Text('Payment Made! \nPickup: ${data.pickup} \nDropoff: ${data.dropoff} \n Price:${data.balance}'),
                    )
              ],
            ),
          ),
        ],
      );
    }
    return const Text("Loading");
  },
)

Solution:

String? qrcode = result?.code??"";

late Message data = Message.fromJson(jsonDecode((qrcode??"")));