appendLastPage method
Append the last page and set the nextPageKey to null
Implementation
@override
void appendLastPage(List<T> newItems) {
final updatedItems = <T>[...(state.itemList ?? []), ...newItems];
state = state.copyWith(
itemList: updatedItems,
nextPageKey: null, // Indicating this is the last page
error: null,
);
}