§ 41. Indebtedness not to be contracted without appropriation. No state officer, employee, board, department or commission shall contract indebtedness on behalf of the state, nor assume to bind the state, in an amount in excess of money appropriated or otherwise lawfully available. This section shall not apply to a case where a statute expressly authorizes the making of a contract or contracts for a stated maximum amount which exceeds the money appropriateed or otherwise available for payments thereon.