[clusterer] Fix error handling when failing to load nodes

On failing to add a node (to the cluster), continue, as time as that node is not the current node.
And if giving up on whole cluster info loading, be sure we clean up and properly report this to the above layer - the last thing we should do is to report success (on load) but have partial, unconsistent data.

Fixes #3473

modules/clusterer/clusterer_mod.c

@@ -469,7 +469,7 @@ static int mod_init(void)
 			LM_ERR("cannot initialize database connection\n");
 			goto error;
 		}
-		if (load_db_info(&dr_dbf, db_hdl, &db_table, cluster_list) < 0) {
+		if (load_db_info(&dr_dbf, db_hdl, &db_table, cluster_list) != 0) {
 			LM_ERR("Failed to load info from DB\n");
 			goto error;
 		}

modules/clusterer/node_info.c

@@ -395,6 +395,7 @@ int load_db_info(db_func_t *dr_dbf, db_con_t* db_hdl, str *db_table,
 
 	if (RES_ROW_N(res) == 0) {
 		LM_WARN("Current node does not belong to any cluster\n");
+		dr_dbf->free_result(db_hdl, res);
 		return 1;
 	}
 
@@ -493,12 +494,17 @@ int load_db_info(db_func_t *dr_dbf, db_con_t* db_hdl, str *db_table,
 		if ((rc = add_node_info(&_, cl_list, int_vals, str_vals)) != 0) {
 			LM_ERR("Unable to add node info to backing list\n");
 			if (rc < 0) {
-				return -1;
+				/* serious error happened, better give up */
+				goto error;
 			} else if (int_vals[INT_VALS_NODE_ID_COL] == current_id) {
 				LM_ERR("Invalid info for local node\n");
-				return -1;
+				/* the node info is bogus, but cannot be skipped
+				 * as it is the current node) */
+				goto error;
 			} else {
-				return 2;
+				/* the node info is bogus, just skip it
+				 * (it's not current node) */
+				continue;
 			}
 		}
 	}