Empty groupOffset in StreamAggExec causes panic

[xzhangxian1008]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

create database test;
use test;
source valid.txt
source error.txt

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

no panic

3. What did you see instead (Required)

We get panic: ERROR 1105 (HY000): runtime error: index out of range [0] with length 0

4. What is your TiDB version? (Required)

a865c86

[ti-chi-bot]

@xzhangxian1008: The label(s) sig/executor cannot be applied, because the repository doesn't have them.

In response to this:

/sig executor

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[xzhangxian1008]

/sig execution

[ti-chi-bot]

@xzhangxian1008: The label(s) sig/executor cannot be applied, because the repository doesn't have them.

In response to this:

/sig executor

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.