Fix the notices that are thrown when loading an invalid FEN

[programarivm]

The chess server will complain with the following PHP notices after trying to load foo as a FEN string:

$ php cli/ws-server.php 
Welcome to PHP Chess Server
Commands available:
/accept {"id":"id"} Accepts a friend request to play a game.
/ascii Prints the ASCII representation of the game.
/castling Gets the castling status.
/captures Gets the pieces captured by both players.
/fen Prints the FEN string representation of the game.
/heuristicpicture Takes a balanced heuristic picture of the current game.
/history The current game's history.
/ischeck Finds out if the game is in check.
/ismate Finds out if the game is over.
/piece {"position":"string"} Gets a piece by its position on the board.
/pieces {"color":["w","b"]} Gets the pieces on the board by color.
/playfen {"fen":"string"} Plays a chess move in shortened FEN format.
/quit Quits a game.
/start {"mode":["analysis","loadfen","playfriend"],"fen":"string","color":["w","b"],"min":"int"} Starts a new game.
/status The current game status.

Listening to commands...
PHP Notice:  Undefined offset: 2 in /home/standard/projects/chess-server/vendor/chesslablab/php-chess/src/FEN/StringToBoard.php on line 89
PHP Notice:  Undefined offset: 2 in /home/standard/projects/chess-server/vendor/chesslablab/php-chess/src/FEN/StringToBoard.php on line 95
PHP Notice:  Undefined offset: 2 in /home/standard/projects/chess-server/vendor/chesslablab/php-chess/src/FEN/StringToBoard.php on line 95
PHP Notice:  Undefined offset: 1 in /home/standard/projects/chess-server/vendor/chesslablab/php-chess/src/FEN/StringToBoard.php on line 52
PHP Notice:  Undefined offset: 2 in /home/standard/projects/chess-server/vendor/chesslablab/php-chess/src/FEN/StringToBoard.php on line 52
PHP Notice:  Undefined offset: 3 in /home/standard/projects/chess-server/vendor/chesslablab/php-chess/src/FEN/StringToBoard.php on line 52

[bofalke]

Hi there, happy learning and coding!

How should this errors be handled? Do you want a special exception to be thrown when an invalid FEN is entered?

[programarivm]

It seems as if the StringToBoard.php class should be fine tuned in order to fix the issue. Not too clear about throwing an exception on this occasion.

[programarivm]

Well, if that's the case and if I'm not very much mistaken a new issue should be opened in the chesslablab/php-chess repo.

[programarivm]

Merged PR chesslablab/php-chess#86