Optoelectronic properties of XIn2S4 (X = Cd, Mg) thiospinels through highly accurate all-electron FP-LAPW method coupled with modified approximations by Yousaf, Masood, Dalhatu, S. A., Murtaza, G., Khenata, R., Sajjad, M., Musa, A., Aliabad, H. A. Rahnamaye, Saeed, M. A.