asio: Fix crash if connect takes longer time than ping interval

src/asio_client_session_impl.cc

@@ -84,7 +84,6 @@ void session_impl::start_resolve(const std::string &host,
                           });
 
   deadline_.async_wait(std::bind(&session_impl::handle_deadline, self));
-  start_ping();
 }
 
 void session_impl::handle_deadline() {
@@ -135,6 +134,8 @@ void session_impl::connected(tcp::resolver::iterator endpoint_it) {
   do_write();
   do_read();
 
+  start_ping();
+
   auto &connect_cb = on_connect();
   if (connect_cb) {
     connect_cb(endpoint_it);