无法在 foreach 循环内为变量设置值（该变量已在其之前声明）。 C#

Question

int PositionEvaluation = 0;
Move FirstDepth;
Move SecondDepth;

foreach (Move move in FirstDepthMoves)
{
    // Try a move
    board.MakeMove(move);
         
    Move[] SecondDepthMoves = board.GetLegalMoves();

    foreach (Move move1 in SecondDepthMoves)
    {
        // Try a second move
        board.MakeMove(move1);
                
        int CurrentEvaluation1 = EvaluatePosition(board, !IsBotWhite);

        // If move be good, then we memorize it
        if (CurrentEvaluation1 > PositionEvaluation)
        {
            // Record this to then play + for seeing its thinking process in Console
            FirstDepth = move;
            SecondDepth = move1;

            PositionEvaluation = CurrentEvaluation1;
        }
           
        board.UndoMove(move1);
    }
        
    board.UndoMove(move);
}

// Here it tells me that it didn't get the value assigned to FirstDepth and SecondDepth from foreach loop
// Idk what to do else about it
Console.WriteLine(FirstDepth);

board.MakeMove(FirstDepth);
Console.WriteLine(EvaluatePosition(board, !IsBotWhite));

Console.WriteLine(SecondDepth);
board.MakeMove(SecondDepth);
Console.WriteLine(EvaluatePosition(board, !IsBotWhite));

board.UndoMove(SecondDepth); 
board.UndoMove(FirstDepth);

在上面的代码中，我在 foreach 循环之前声明一个变量，然后在每个循环中为它分配所需的值。但是当我尝试将其写入控制台并对其进行移动时，它告诉我它未分配。

我曾尝试为之前的变量设置一个值，但这只是保留了该值而不更改它：

Move FirstDepth = moveToPlay;
Move SecondDepth = moveToPlay;

我也尝试过设置一个临时值来获取它，但也没有成功。

为了了解更多背景信息，这是我尝试由 SebLeague 创建的小型国际象棋机器人竞赛的一部分。这是它的链接：https://github.com/SebLague/Chess-Challenge

这是 MyBot 的完整文件：

using ChessChallenge.API;
using System;

public class MyBot : IChessBot
{
    const PieceType Pawn = (PieceType)1;
    const PieceType Knight = (PieceType)2;
    const PieceType Bishop = (PieceType)3;
    const PieceType Rook = (PieceType)4;
    const PieceType Queen = (PieceType)5;

    public Move Think(Board board, Timer timer)
    {
        bool IsBotWhite = board.IsWhiteToMove;
        Move[] FirstDepthMoves = board.GetLegalMoves();

        Random rng = new();
        Move moveToPlay = FirstDepthMoves[rng.Next(FirstDepthMoves.Length)];
        int PositionEvaluation = 0;

        Move FirstDepth = moveToPlay;
        Move SecondDepth = moveToPlay;

        foreach (Move move in FirstDepthMoves)
        {
            //Try a move
            board.MakeMove(move);

            FirstDepth = moveToPlay;
            SecondDepth = moveToPlay;
            
            Move[] SecondDepthMoves = board.GetLegalMoves();

            foreach (Move move1 in SecondDepthMoves)
            {
                // Try a second move
                board.MakeMove(move1);
                    
                int CurrentEvaluation1 = EvaluatePosition(board, !IsBotWhite);
                // If move be good, then we memorize it
                if (CurrentEvaluation1 > PositionEvaluation)
                {
                    //Record this to then play + for seeing its thinking process in Console
                    FirstDepth = move;
                    SecondDepth = move1;

                    PositionEvaluation = CurrentEvaluation1;
                }
               
                board.UndoMove(move1);
            }
            
            board.UndoMove(move);
        }

        // Here it tells me that It didnt get the value assigned to FirstDepth and SecondDepth from foreach loop
        //Idk what to do else about it
        Console.WriteLine(FirstDepth);
        board.MakeMove(FirstDepth);
        Console.WriteLine(EvaluatePosition(board, !IsBotWhite));
        Console.WriteLine(SecondDepth);
        board.MakeMove(SecondDepth);
        Console.WriteLine(EvaluatePosition(board, !IsBotWhite));
        board.UndoMove(SecondDepth); 
        board.UndoMove(FirstDepth);
        return FirstDepth;
    }
    
    int EvaluatePosition(Board board, bool IsWhite)
    {
        //the E stands for Enemy
        PieceList Pawns = board.GetPieceList(pieceType: Pawn, white: IsWhite);
        PieceList Knights = board.GetPieceList(pieceType: Knight, white: IsWhite);
        PieceList Bishops = board.GetPieceList(pieceType: Bishop, white: IsWhite);
        PieceList Rooks = board.GetPieceList(pieceType: Rook, white: IsWhite);
        PieceList Queens = board.GetPieceList(pieceType: Queen, white: IsWhite);

        bool IsWhiteE = !IsWhite;

        PieceList PawnsE = board.GetPieceList(pieceType: Pawn, white: IsWhiteE);
        PieceList KnightsE = board.GetPieceList(pieceType: Knight, white: IsWhiteE);
        PieceList BishopsE = board.GetPieceList(pieceType: Bishop, white: IsWhiteE);
        PieceList RooksE = board.GetPieceList(pieceType: Rook, white: IsWhiteE);
        PieceList QueensE = board.GetPieceList(pieceType: Queen, white: IsWhiteE);

        int TotalEval = ((Pawns.Count * 1) + (Knights.Count * 3) + (Bishops.Count * 3) + (Rooks.Count * 5) + (Queens.Count * 9)) - ((PawnsE.Count * 1) + (KnightsE.Count * 3) + (BishopsE.Count * 3) + (RooksE.Count * 5) + (QueensE.Count * 9));

        if (board.IsDraw())
        {
            TotalEval = -100;
        }
        else if (board.IsInCheckmate())
        {
            TotalEval = 100;
        }

        if (board.IsInCheck())
        {
            TotalEval = TotalEval +  1;
        } 
        
        return -TotalEval;
    }
}