message: fix ek::leaf_array_t
diff: @@ -304,7 +304,7 @@ namespace detail {
  template <typename T> struct leaf_array<enable_if_array_t<T>, T> {
  using type = std::conditional_t<
  is_array_v<value_t<T>>,
  - value_t<T>, T
  + leaf_array_t<value_t<T>>, T
  >;
  };
  