libwebsockets < 4.0.21 includes bad assert on return value of SSL_get_error

using libwebsockets 4.0.20, the backtrace shows assertion here:
int lws_ssl_get_error(struct lws *wsi, int n)
{
    int m;

    if (!wsi->tls.ssl)
        return 99;

    m = SSL_get_error(wsi->tls.ssl, n);
    lwsl_debug("%s: %p %d -> %d (errno %d)\n", __func__, wsi->tls.ssl, n, m,
           errno);

    assert (errno != 9);

    return m;
}
here is same function in 4.0.21
int lws_ssl_get_error(struct lws *wsi, int n)
{
    int m;

    if (!wsi->tls.ssl)
        return 99;

    m = SSL_get_error(wsi->tls.ssl, n);
    lwsl_debug("%s: %p %d -> %d (errno %d)\n", __func__, wsi->tls.ssl, n, m,
           errno);

    return m;
}

further https://github.com/warmcat/libwebsockets/issues/2007