Flutter 2: From List null safety create a children row with mapIndex

Question

Since the update of flutter of null safety I don't understand anything of what is happening.

I am trying from a list on a children to create a Row of icons but I don't succeed (here the mapIndex can't be used because of the null safety (whereas in an older version it would worked)):

import 'package:flutter/material.dart';

class NavigationBar extends StatefulWidget {
  final List<Map<String, dynamic>>? icons;

  const NavigationBar({
    @required this.icons,
    Key? key
  }) : super(key: key);

  @override
  _NavigationBarState createState() => _NavigationBarState();
}

class _NavigationBarState extends State<NavigationBar> {
  @override
  Widget build(BuildContext context) {
    return Container(
      width: double.infinity,
      height: 40,
      child: Row(
        children: widget.icons.mapIndex((i, icon) {return Container();})
      ),
    );
  }
}

Answer 1

The first problem was the missing of the collection import (so I couldn't use mapIndex)

The second is the verification of the null. I don't know if it is the better solution but here my version where I check the null value :

import 'package:flutter/material.dart';

import 'package:collection/collection.dart';

class NavigationBar extends StatefulWidget {
  final List<Map<String, dynamic>>? icons;

  const NavigationBar({
    @required this.icons,
    Key? key
  }) : super(key: key);

  @override
  _NavigationBarState createState() => _NavigationBarState();
}

class _NavigationBarState extends State<NavigationBar> {
  @override
  Widget build(BuildContext context) {
    return Container(
      color: Color.fromARGB(255, 12, 10, 10),
      width: double.infinity,
      height: 40,
      child: Row(
        children: widget.icons == null ? [] :
          widget.icons!.mapIndexed((index, element) =>
          IconButton(
            onPressed: () {},
            icon: widget.icons![0]['icon'],
            color: Colors.white,
          )).toList()
      ),
    );
  }
}