import json


def compose_label(label_string):
    """Compose a valid label for Lira from a string of object.

    Args:
        label_string (str): A valid string of dictionary.

    Returns:
        dict: A valid dict that describes a Cromwell workflow label.

    """
    try:
        return json.loads(label_string)
    except (json.decoder.JSONDecodeError, TypeError):
        return None