Defects and irregularities in any proceeding had in substantial compliance with this chapter, when the issue is for a lawful purpose and is unaffected by fraud and does not exceed any constitutional or statutory limitation of amount, do not invalidate the bonds issued nor the indebtedness incurred after the bonds have been sold and the proceeds thereof received by the municipality, nor after the performance of a contract has been entered upon by a party who is to receive the said bonds or the proceeds thereof as consideration for said contract.