Failed assertion line 5120 pos 12: 'child = _child' is not true

I am trying to create a listview with API data using bloc pattern following is the error:

'package:flutter/src/widgets/framework.dart': Failed assertion: line 5120 pos 12: 'child == _child': is not true.

My list file:

import 'package:Instant_Feedback/Dashboard/PeopleList/bloc/bloc.dart';
import 'package:Instant_Feedback/People/strongConnection_model.dart';
import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';

class PeopleListing extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => _PeopleListingState();
}
class _PeopleListingState extends State<PeopleListing> {
  PeopleListBloc peopleBloc;
  @override
  void initState() {
    super.initState();
    peopleBloc = BlocProvider.of<PeopleListBloc>(context);
    peopleBloc.dispatch(DisplayPeopleList());
  }

  @override
  Widget build(BuildContext context) {
    return BlocBuilder(
      bloc: peopleBloc,
      builder: (context, state){
        if (state is PeopleUninitializedState) {
          print("PeopleUninitializedState");
        } else if (state is PeopleFetchingState) {
          print("PeopleFetchingState");
        } else if (state is PeopleFetchingState) {
          print("PeopleFetchingState");
        } else {
          final stateAsPeopleFetchedState = state as PeopleFetchedState;
          final players = stateAsPeopleFetchedState.people;
          return buildPeopleList(players);
        }
      },
    );
  }

Widget buildPeopleList(List<StrongConnection_model> people) {
    print(people.length);
    return Container(
      child: Text('sdf sdkfh kdj'),
    );
  }
}

Error:

Problem is, builder() expects a widget & you're not returning a valid widget in the if/else if conditions. Try changing your code to the below version.

@override
Widget build(BuildContext context) {
    return BlocBuilder(
        bloc: peopleBloc,
        builder: (context, state){
            if (state is PeopleUninitializedState) {
                <!-- Expects A Widget -->
                print("PeopleUninitializedState");
                return SizedBox();
            } else if (state is PeopleFetchingState) {
                <!-- Expects A Widget -->
                print("PeopleFetchingState");
                return SizedBox();
            } else if (state is PeopleFetchingState) {
                <!-- Expects A Widget -->
                print("PeopleFetchingState");
                return SizedBox();
            } else {
                final stateAsPeopleFetchedState = state as PeopleFetchedState;
                final players = stateAsPeopleFetchedState.people;
                return buildPeopleList(players);
            }
        },
    );
}