Catch and handle exceptions. Invalid FEN causes fatal error #8
Description
4k3/8/8/8/8/5N2/8/1N2K3 w KQkq d6 0 5
Fatal error: Uncaught Exception: Invalid FEN - Castling permissions set to TRUE but rook is missing in D:\Dropbox\Code\chess\chess_v2.2 [before putting on Red Dragon Web Design]\models\ChessRulebook.php on line 646
8/8/2n2n2/3pp3/4P3/3P1N2/PPP1BPPP/RNBQK2R w KQkq d6 0 5
Fatal error: Uncaught TypeError: Argument 3 passed to ChessRulebook::square_is_attacked() must be an instance of ChessSquare, null given, called in D:\Dropbox\Code\chess\chess_v2.2 [before putting on Red Dragon Web Design]\models\ChessRulebook.php on line 675 and defined in D:\Dropbox\Code\chess\chess_v2.2 [before putting on Red Dragon Web Design]\models\ChessRulebook.php on line 794