// Allow custom FEN (and check it) only for individual challenges
if (c.fen.length > 0 && !!c.to) {
if (!V.IsGoodFen(c.fen)) return "Errors in FEN";
// Allow custom FEN (and check it) only for individual challenges
if (c.fen.length > 0 && !!c.to) {
if (!V.IsGoodFen(c.fen)) return "Errors in FEN";