Flutter App gets Stuck when Future Builder is in ConnectionState.waiting

Question

I am using Flutter Future Builder with ListView which display data loaded from an API. When the Future Builder is in ConnectionState.waiting the app gets Stuck.

 FutureBuilder<List<int>>(
          future: totals,
          builder: (BuildContext context, AsyncSnapshot<List<int>> snapshot) {
            switch (snapshot.connectionState) {
              case ConnectionState.none: return new Text('Press button to start');
              case ConnectionState.active:
              case ConnectionState.waiting: return new Text('Awaiting result...');
              case ConnectionState.done:
                if (snapshot.hasError)
                  return new Text('Error: ${snapshot.error}');
                else
                  return RefreshIndicator(
                      onRefresh: _refresh,
                      child: ListView(
                        children: [
                          Column(
                            children: [
                              Text("Total Confirmed : ${snapshot.data[0]}"),
                              Text("Total Active : ${snapshot.data[1]}"),
                              Text("Today Confirmed : ${snapshot.data[2]}"),
                            ],
                          ),
                        ],
                      )
                  );
                  break;
              default:
                return null;
            }
          },
        )
  Future<List<int>> totals;

  void initState() {
    super.initState();
    totals=_fetchtotals();
  }

  Future<void> _refresh() async{
    totals=_fetchtotals();
  }
  Future<List<int>> _fetchtotals() async {
      //loading data from API and returning
      return totals;
  }