test(chat): clear borrowed fault selector before its scope ends

tests/test_chat_profile.c

@@ -269,6 +269,7 @@ static void owner_faults(struct UTUN_INSTANCE* inst) {
         assert(topo_node_sqlite_member_owner_put(inst->topo_sqlite_db, channel, inst->node_id, NULL, NULL, 0) < 0 && fault == F_NONE);
         assert(sqlite3_exec(inst->topo_sqlite_db, "ROLLBACK", NULL, NULL, NULL) == SQLITE_OK);
     }
+    target = NULL;
     printf("PASS owner block:%u SQL faults/retries,NULL binds,and failed standalone ROLLBACK TO never commits partial owner data\n", cases);
 }