(a) Notwithstanding the person's signature, a person ceases to be a party to, and bound by, a shareholders' agreement when the person ceases to be a shareholder of the close corporation unless:
(1) the person's attempted cessation was in violation of Section 21.721 or the shareholders' agreement; or
(2) the shareholders' agreement provides to the contrary.
(b) Cessation as a party to a shareholders' agreement or as a shareholder does not relieve a person of liability the person may have incurred for breach of the shareholders' agreement.