error in snopshot

[poyjie]

lib/main.dart:43:47: Error: A value of type 'List

?' can't be assigned to a variable of type 'List' because 'List?' is nullable and 'List' isn't.

• 'List' is from 'dart:core'.
• 'Article' is from 'package:news_app/model/article_model.dart' ('lib/model/article_model.dart').
  List articles = snapshot.data;