ctf challenge add fails

Hello. I am new to ctfcli, I just did `ctf init` and `ctf challenge add https://github.com/misogihagi/my-ctf-challenges.git` andgot the following error:
```
fatal: ambiguous argument 'HEAD': unknown revision or path not in the working tree.
Use '--' to separate paths from revisions, like this:
'git [...] -- [...]'
fatal: working tree has modifications. Cannot add.
Could not add the challenge repository. Please check git error messages above.
````

Is this a known bug?