Mapping image data to the list .List<T>', is a potentially non-nullable type?-CodePudding

I am trying to upload image from the Assets folder image but getting an error while trying to map the list of image. I have created CarouselModel and trying to map. Error as The body might complete normally, causing 'null' to be returned, but the return type, 'List<T>', is a potentially non-nullable type. How can It be solved? Thank you in advance.

class model :

class CarouselModel {
  String image;
  CarouselModel(this.image);    }

List<CarouselModel> carsouels =
    carsouelsData.map((item) => CarouselModel(item['image']!)).toList();    
var carsouelsData = [
  {"image": "images/pic1.jpg"},
  {"image": "images/pic2.png"},
  {"image": "images/pic3.jpg"},
];

Trying to map using:

List<T> map<T>(List list, Function handler) {  
    List<T> result = [];
    for (var i = 0; i < list.length; i  ) {
      result.add(handler(i, list[i]));      
    }
  }

View code:

  body: Container(
    child: ListView(
      physics: ClampingScrollPhysics(),
      children: <Widget>[
        Padding(
          padding: EdgeInsets.only(left: 16, right: 16),
          child: Text(
            'welcome to the beautiful world