XFR: fix resource leak on error recovery when adding node

CID: 1088834

src/libknot/updates/xfr-in.c

@@ -1744,6 +1744,7 @@ static knot_node_t *xfrin_add_new_node(knot_zone_contents_t *contents,
 	}
 	if (ret != KNOT_EOK) {
 		dbg_xfrin("Failed to add new node to zone contents.\n");
+		knot_node_free(&node);
 		return NULL;
 	}