connection disconnected when select * from t as of timestamp NULL

[lcwangchao]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

create table t(a int);
select * from t as of timestamp NULL;

2. What did you expect to see? (Required)

Error, but connection should not disconnect

3. What did you see instead (Required)

The connection disconnected and have an internal error:

mysql> select * from t as of timestamp NULL;
ERROR 1105 (HY000): interface conversion: interface {} is nil, not types.Time

4. What is your TiDB version? (Required)

master

mysql> select tidb_version();
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| tidb_version()                                                                                                                                                                                                                                                                                                                   |
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Release Version: v6.0.0-alpha
Edition: Community
Git Commit Hash: 9fcc6b090b02c8351aba4ee8a7f072e0e0c840e0
Git Branch: heads/refs/tags/v6.0.0-alpha
UTC Build Time: 2022-03-13 14:52:09
GoVersion: go1.16.4
Race Enabled: false
TiKV Min Version: v3.0.0-60965b006877ca7234adaced7890d7b029ed1306
Check Table Before Drop: false |
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.01 sec)