代码打断点运行到user_profile.save()保存数据库的时候报错，显示ValueError: The view users.views.RegisterView didn't return an HttpResponse object. It returned None instead.

这是view

class RegisterView(View):
    def get(self, request):
        register_form = RegisterForm()
        return render(request, 'register.html', {'register_form': register_form})

    def post(self, request):
        register_form = RegisterForm(request.POST)
        if register_form.is_valid():
            user_name = request.POST.get('email', '')  # 取request中POST的user_name和pass_word用于后面判断
            pass_word = request.POST.get('password', '')
            user_profile = UserProfile()
            user_profile.username = user_name
            user_profile.email = user_name
            user_profile.is_active = False
            user_profile.password = make_password(pass_word)
            user_profile.save()
            send_register_email(user_name, 'register')
            return render(request, 'login.html')