Hi, When `git stash` on detached HEAD I got a segmentation fault. I am using git 2.45.2 on OSX/Darwin. Furthermore the culprit is EXC_BAD_ACCESS on `repo_find_unique_abbrev_r` because `oid` is invalid. The `oid` was obtained from NULL `lookup_commit` in `do_create_stash`. The result from `lookup_commit` should be checked for validation to avoid null access. https://github.com/git/git/blob/7b0defb3915eaa0bd118f0996e8c00b4eb2dc1ca/builtin/stash.c#L1380 Thanks.
