adding assignments fails if gitconfig can't be found or written to

[lockejan]

Bug Report

git-team version: 1.7.0
go version: 1.17.7

failure description

Invoking git team assignments add noujz "Mr. Noujz <[email protected]>" exits with error: exit status 255 if no $HOME/.gitconfig is present.
This also happens if the file is read-only.

Background:
It's possible to store gitconfig under $XDG_HOME, e.g. $HOME/.config/git/config
Git checks a set of paths for configurations on every invocation.

expected behaviour description

Creation of $HOME/.gitignore or another distinct file for git-team.
Alternatively or additionally a graceful exit with an explanation error message or offering to create a .gitconfig.

Note: Some approaches like home-manager favours immutable configuration, meaning that wherever gitconfig is put it is read-only by default. That's not always a given and it's possible to make them writeable as well.

PS:This also happens for other git-team cmd's that rely on the existence of the file like git-team disable.

[hekmekk]

Finally had some spare time to implement a "fix" with revision 74119e2.

Decided for printing more helpful error messages for the time being as it feels right to me that git-team as a git sub command makes use of the git config command for configuration and useful error messages have definitely been missing here.