def METHOD_NAME(indexer_id):
    """
    Check that the provided indexer_id is valid and corresponds with a known show
    :param indexer_id: The indexer id to check
    :return: A tuple containing:
     - an error message if the indexer id is not correct, ``None`` otherwise
     - the show object corresponding to ``indexer_id`` if it exists, ``None`` otherwise
    """
    try:
        indexer_id = int(indexer_id)
    except (TypeError, ValueError):
        return "Invalid show ID", None
    try:
        show = Show.find(settings.showList, indexer_id)
    except MultipleShowObjectsException:
        return "Unable to find the specified show", None
    return None, show