(a) The following are not liable for damages arising from the performance of a governmental function of a Type A corporation or the authorizing municipality:
(1) the corporation;
(2) a director of the corporation;
(3) the municipality;
(4) a member of the governing body of the municipality; and
(5) an employee of the corporation or municipality.
(b) For purposes of Chapter 101, Civil Practice and Remedies Code (Texas Tort Claims Act), a Type A corporation is a governmental unit and the corporation's actions are governmental functions.