index out of range when create gbk charset enum column

[xiongjiwei]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

create table t(a enum('a', 0x91) charset gbk);

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

no panic

3. What did you see instead (Required)

4. What is your TiDB version? (Required)

[xiongjiwei]

dup of #30798, they have the same root cause

[github-actions]

Please check whether the issue should be labeled with 'affects-x.y' or 'fixes-x.y.z', and then remove 'needs-more-info' label.

[tangenta]

They are not the same root cause.

[github-actions]

Please check whether the issue should be labeled with 'affects-x.y' or 'fixes-x.y.z', and then remove 'needs-more-info' label.