Undo git commit results in fatal error when the commit to undo is the initial commit

[cesarcoatl]

Describe the bug When the commit to undo is the initial commit, there is no HEAD~, so undoing this commit results in the following error:

$ ugit
fatal: ambiguous argument 'HEAD~': unknown revision or path not in the working tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'

To Reproduce

$ cd ~
$ mkdir git-repo
$ cd git-repo
$ git init
Initialized empty Git repository in ~/git-repo/.git/
$ touch README.md
$ git add README.md
$ git commit -a -m "chore: initial commit"
$ ugit
Undo your last oopsie in Git 🙈️
Press ctrl+c to exit anytime
# 1 Undo git commit
# Choose git commit
fatal: ambiguous argument 'HEAD~': unknown revision or path not in the working tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'

Expected behavior The commit should be undone.

Screenshots If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

macOS

• OS: macOS 10.15
• Bash Version: 5.1.16(1)
• FZF Version: 0.30.0 (brew)
• Git Version: 2.35.1

Windows

• OS: Windows 10
• Bash Version: 4.4.23(2)
• FZF Version: 0.30.0 (2093667)
• Git Version: 2.35.1.windows.2

Additional context vscode fixed this same issue via: https://github.com/microsoft/vscode/pull/47578

[kopalchakravarty]

@Bhupesh-V Hi, I'd like to work on this issue