Issue #2478663 by caesius, sanja_m, slashrsm, alphawebgroup, Drews_man, Sagar Ramgade, Traverus, larowlan, smustgrave, Berdir, lauriii, catch, mbovan: UniqueFieldValueValidator works only with single value fields

Issue #78292 by BrockBoland, chx, Traverus, thoufek, patrickd, sun: Fixed Select element with empty options triggers PHP warning.