Some bug fixes

Sources/Engine/Board.swift

@@ -2,12 +2,14 @@ enum Event {
 	case kingInCheck(_ by: Piece, on: King)
 	case piecePinned(from: Piece, on: Piece)
 }
+
 protocol EventDelegate {
 	func notify(_ event: Event)
 	func movePiece(_ piece: Piece, to dst: Square.Position) throws
 	func addPieceToTarget(_ piece: Piece, target: Square.Position)
 	func getSquareInfo(on pos: Square.Position) -> Square?
 }
+
 public class Board: CustomStringConvertible, EventDelegate {
 	public typealias Grid = [[Square]]
 
@@ -77,10 +79,10 @@ public class Board: CustomStringConvertible, EventDelegate {
 	}
 
 	internal func addPieceToTarget(_ piece: Piece, target: Square.Position) {
-		guard var square = self[target] else {
+		guard self[target] != nil else {
 			return
 		}
-		square.targetted.insert(piece)
+		squares[target.index!].targetted.insert(piece)
 	}
 
 	public private(set) var halfMoveClock: UInt8 = 0
@@ -189,7 +191,10 @@ public class Board: CustomStringConvertible, EventDelegate {
 		}
 
 		try piece.move(to: dst)
-		#warning("May need to clear threatenedSquares before hand.")
+		threatenedSquares = [
+			.White: [],
+			.Black: [],
+		]
 		for square in squares where square.piece != nil {
 			let p = square.piece!
 			p.getLegalPosition()
@@ -320,13 +325,11 @@ public class Board: CustomStringConvertible, EventDelegate {
 			boardString += String(_rank) + " \(UnicodeBar.VerticalBar)"
 			rank.forEach { square in
 				let p = square.piece?.unicodeRepresentation ?? " "
+				h1 = def
 				if let c = colors {
-					for (color, s) in c {
-						h1 = def
-						if (s.contains { $0 == square.position }) {
-							h1 = color
-							break
-						}
+					for (color, s) in c
+					where (s.contains { $0 == square.position }) {
+						h1 = color
 					}
 				}
 				boardString +=