DNAMES: Server crashes in Item_func_dyncol_exists::val_int => String::charset with NULL as a column name/number

Description

This is similar to MDEV-490, but since it comes to the crash from a different function, and not all functions produce the crash, I'm filing it separately.

Environment

None

Assignee

Oleksandr Byelkin

Reporter

Elena Stepanova

Labels

None

Fix versions

Priority

Major
Configure