Wrapper for `click.edit` that raises an error when None is returned.

def editor(*args, **kwargs):
    '''
    Wrapper for `click.edit` that raises an error when None is returned.
    '''
    result = click.edit(*args, **kwargs)
    if result is None:
        msg = 'Editor exited without saving, command aborted'
        raise click.ClickException(msg)
    return result