Doesn't work in detached HEAD state

[mrPjer]

It seems that this utility does not work when the repository is in detached HEAD state.

Running:

git checkout @~0
git hours

Results in:

Error: Reference 'refs/remotes/(HEAD/HEAD' not found
    at Error (native)

This is the reason why Travis CI builds fail with Uncaught SyntaxError: Unexpected end of input, which you reported in travis-ci/travis-ci#2493 and this can be confirmed by printing out stderror in any of the tests (the above error is displayed).