Fix bug during copy when in the config the value of pool_reserve_prep…

…ared_statement is equal to yes (#562)

* fixed

* fmt

* fix

sources/frontend.c

@@ -997,6 +997,7 @@ static od_frontend_status_t od_frontend_remote_client(od_relay_t *relay,
 
 	od_frontend_status_t retstatus = OD_OK;
 	machine_msg_t *msg;
+	msg = NULL;
 	bool forwarded = 0;
 	switch (type) {
 	case KIWI_FE_COPY_DONE:
@@ -1513,7 +1514,8 @@ static od_frontend_status_t od_frontend_remote_client(od_relay_t *relay,
 	}
 
 	/* If the retstatus is not SKIP */
-	if (route->rule->pool->reserve_prepared_statement && forwarded != 1) {
+	if (route->rule->pool->reserve_prepared_statement && forwarded != 1 &&
+	    msg != NULL) {
 		msg = kiwi_fe_copy_msg(msg, data, size);
 		od_write(&server->io, msg);
 		retstatus = OD_SKIP;