The existence of or a performance under a shareholders' agreement authorized by this subchapter is not a ground for imposing personal liability on a shareholder for an act or obligation of the corporation by disregarding the separate existence of the corporation or otherwise, even if the agreement or a performance under the agreement:
(1) treats the corporation as if the corporation were a partnership or in a manner that otherwise is appropriate only among partners;
(2) results in the corporation being considered a partnership for purposes of taxation; or
(3) results in failure to observe the corporate formalities otherwise applicable to the matters governed by the agreement.