[Fix] Plan new event on HTTP errors

Issue: #1898
MFH: rspamd-1.6

src/libutil/map.c

@@ -755,6 +755,7 @@ read_data:
 	else {
 		msg_info_map ("cannot load map %s from %s: HTTP error %d",
 				bk->uri, cbd->data->host, msg->code);
+		goto err;
 	}
 
 	MAP_RELEASE (cbd, "http_callback_data");