PizzaManager-errorhandling.swift

func fillWithData() {
    PizzaManager().all()
        .subscribe(onNext: { [weak self] pizza in
            self?.pizzaViewModel.value = pizza
        }, onError: { [weak self] _ in
            if self?.pizzaViewModel.value.count == 0 {
                self?.pizzaCollectionView.backgroundView = NetworkErrorView(withAction: {
                    self?.fillWithData()
                })
            }
        }).disposed(by: self.disposeBag)
}