Flutter Error: RangeError (index): Invalid value: Not in range 0..2, inclusive: 3

You should pass the itemCount parameter to the ListView.builder to allow it to know the item count

Widget getList() {
  List<String> list = getListItems();
  ListView myList = new ListView.builder(
    itemCount: list.length,
    itemBuilder: (context, index) {
    return new ListTile(
      title: new Text(list[index]),
    );
  });
  return myList;
}