When using the "add" feature of repo, if you call it with two arguments : options and callback, there is an error because command line executed is "git add [Object object]".
I was trying with repo.add({"A":true}, function(){...}), that is not working.
When replacing "files" first argument with null, using repo.add(null, {"A": true}, function(){...}), it is working and runs "git add -A"
Maybe just confusing documentation because options is not specified ?