fix(f24 p4): misleading error (#780)

* fix(f24 p4): misleading error

* fix: check order

Author: unw9527

test/txn/txn_index_concurrent_test.cpp

@@ -150,7 +150,8 @@ TEST(TxnIndexTest, DISABLED_IndexConcurrentUpdateTest) {  // NOLINT
           if (add_delete_insert) {
             StringVectorWriter data_writer;
             BUSTUB_ENSURE(bustub->ExecuteSqlTxn(generate_select_sql(i), data_writer, txn), "cannot retrieve data");
-            BUSTUB_ENSURE(data_writer.values_.size() == 1, "more than 1 row fetched??");
+            BUSTUB_ENSURE(!data_writer.values_.empty(), "no row fetched??");
+            BUSTUB_ENSURE(data_writer.values_.size() == 1, "more than one row fetched??");
             const auto b_val = std::stoi(data_writer.values_[0][0]);
             BUSTUB_ENSURE(bustub->ExecuteSqlTxn(generate_delete_sql(i), data_writer, txn), "cannot delete data");
             BUSTUB_ENSURE(bustub->ExecuteSqlTxn(generate_txn_insert_sql(b_val, i), data_writer, txn),