class needs public declaration

Author: WardBrian

stan/math/prim/functor/operands_and_partials.hpp

@@ -55,6 +55,7 @@ class ops_partials_edge;
  */
 template <typename ViewElt, typename Op>
 class ops_partials_edge<ViewElt, Op, require_st_arithmetic<Op>> {
+  public:
   using inner_op = std::conditional_t<is_eigen<value_type_t<Op>>::value,
                                       value_type_t<Op>, Op>;
   using partials_t = empty_broadcast_array<ViewElt, inner_op>;