Casting DatabaseEvent snapshot.value to a specific type in Flutter

Question

I'm trying to retrieve data from a DatabaseEvent event type. The data I have on the database is this in this layout

Basically some users id and each user has a a different number of menu orders. What I want to do is retrieve each order of each user and do something with it.

Right now I'm using

 Map data = event.snapshot.value as Map;

but since it's a dynamic cast, it sometimes retrieves the values as a List of Objects and sometimes as a Map of Objects..

For example if the orders number are in order as the picture above (order number 1 and number 2), it retrieves the data like this :

{ZqsrXaqhXbPFgPTvIbnxRNw3bX42: [null, {number: 1, quantity: 3}], tzqjzgzy: [null, {number: 1, quantity: 2}, {number: 2, quantity: 3}]}

as a List and it retrieves a null because there is no order 0. If I change the orders from 1 and 2 to 2 and 3, it gives me the same result but with two nulls at the beginning.

If I change the orders number to more random numbers, it retrieves them correctly as a Map, or more specifically as an _InternalLinkedHashMap<Object?, Object?>.

{ZqsrXaqhXbPFgPTvIbnxRNw3bX42: {12: {number: 12, quantity: 2}, 24: {number: 24, quantity: 3}}}

I want to retrieve it everytime in the same way so I tried casting the snapshot.value in different ways like so

Map<dynamic, Map> data =
              event.snapshot.value as Map<dynamic, Map>;

but everytime I do I don't get any data.

This is my code right now

.then((DatabaseEvent event) {
        if (event.snapshot.exists) {
          
          Map<dynamic, dynamic> data =
              event.snapshot.value as Map;

         
          //sum all orders
          Map<int, Map> allOrders = {};

          data.forEach((key, userOrders) {
          
            userOrders.forEach((key, order) {
            
              allOrders[order['number']] = {
                'number': order['number'],
                'quantity': allOrders[order['number']] != null
                    ? allOrders[order['number']]!['quantity'] +
                        order['quantity']
                    : 0 + order['quantity'],
              };
            });
          });
          return allOrders;
        } else {
          throw Exception('Error snapshot does not exist');
        }
});