Method unload

include/boost/leaf/error.hpp:495–503

    template <class E>
    inline void slot<E>::unload( int err_id ) noexcept(!BOOST_LEAF_CFG_CAPTURE)
    {
        BOOST_LEAF_ASSERT(err_id);
        if( this->key() != err_id )
            return;
        if( impl * p = get_slot<E>() )
            if( !p->has_value(err_id) )
                *p = std::move(*this);
    }

    template <class E>
    BOOST_LEAF_CONSTEXPR inline int load_slot( int err_id, E && e ) noexcept(!BOOST_LEAF_CFG_CAPTURE)