def get_error(e, path=''):
    """ Recursively dereferences `path` (a period-separated sequence of dict
    keys) in `e` (an error dict or value), returns the final resolution IIF it's
    an str, otherwise returns None
    """
    for k in (path.split('.') if path else []):
        if not isinstance(e, dict):
            return None
        e = e.get(k)

    return e if isinstance(e, str) else None