Force a compile time error in a template specialization

I recently started to learn modern template metaprogramming and I wrote myself an index_of function for types.

template<std::size_t Index, class C, class A> struct mp_index_of_impl{};
template<std::size_t Index, class C,template<class...> class A,class ...Ts>
struct mp_index_of_impl<Index,C,A<C,Ts...>>{
    using type = std::integral_constant<std::size_t,Index>;
};
template<std::size_t Index, class C,template<class...> class A,class ...Ts,class T1>
struct mp_index_of_impl<Index,C,A<T1,Ts...>>{
    using type = typename mp_index_of_impl<Index + 1,C,A<Ts...>>::type;
};
template<std::size_t Index, class C,template<class...> class A> struct mp_index_of_impl<Index,C,A<>>{
    //static_assert(false,"Does not contain type");
    using type = std::integral_constant<std::size_t,0>;
};

The problem is my last specialization

template<std::size_t Index, class C,template<class...> class A> 
struct mp_index_of_impl<Index,C,A<>>{
      //throw a compile error here
};

I tried to use static_assert like this

template<std::size_t Index, class C,template<class...> class A> struct mp_index_of_impl<Index,C,A<>>{
    static_assert(false,"Does not contain type");
};

But this will throw a compile error every time, even if it is not matched.

I want to throw a compile error with a custom error message if this template specialization is matched. How would I do this?