How to resolve non-nullable error in Flutter?
You must initialize the CategoryModel.categories variable, since this variable has been defined as a non-nullable it cant be left uninitialized as this is null.
You should update the model class and set an initial value for the categories, for example
class CategoryModel { static List<Category> categories = List.empty();}
Your variable static List<Category> categories; is a List<Category> type. Since its non-nullable, the value it holds can never be null. So from the initialization you need to supply a value.
You can solve this in a few ways. The easiest would be to give an initial value:
static List<Category> categories = [];Other ways to handle this without giving an initial value would be to make the variable nullable, or marking it with a late initialization keyword. To read more of this, check the oficial documentation here.