With respect to:
the general assembly covenants with the commission and the purchasers or owners of the bonds described in this section that this chapter will not be repealed or amended in any manner that will adversely affect the collection of the tax imposed under this chapter or the money deposited in the convention and visitor promotion fund, as long as the principal of or interest on any bonds, or the lease rentals due under any lease, are unpaid.
IC 6-9-11-3.9