Python TypeError：无法解压不可迭代的 NoneType 对象错误

我看了其他答案，但它们似乎对我不起作用，或者我可能只是做错了什么，或者不理解在这个代码的上下文中我应该做什么.在第78行，它讨论了如何存在非类型值，即使我为这两个变量分配了一个值.

下面是一个类似问题的链接(我认为):

我认为错误代码就在这里:

def check_win(turn, gamestate):
    if turn == 1:
        if gamestate[0] == gamestate[1] == gamestate[2] != '-' or gamestate[3] == gamestate[4] == gamestate[5] != '-' or gamestate[6] == gamestate[7] == gamestate[8] != '-':
            winner = 1
            win = True
            return winner, win
        elif gamestate[0] == gamestate[3] == gamestate[6] != '-' or gamestate[1] == gamestate[4] == gamestate[7] != '-' or gamestate[2] == gamestate[5] == gamestate[8] != '-':
            winner = 1
            win = True
            return winner, win
        elif gamestate[0] == gamestate[4] == gamestate[8] != '-' or gamestate[2] == gamestate[4] == gamestate[6] != '-':
            winner = 1
            win = True
            return winner, win
    elif turn == 2:
        if gamestate[0] == gamestate[1] == gamestate[2] or gamestate[3] == gamestate[4] == gamestate[5] or gamestate[6] == gamestate[7] == gamestate[8]:
            winner = 2
            win = True
            return winner, win
        elif gamestate[0] == gamestate[3] == gamestate[6] or gamestate[1] == gamestate[4] == gamestate[7] or gamestate[2] == gamestate[5] == gamestate[8]:
            winner = 2
            win = True
            return winner, win
        elif gamestate[0] == gamestate[4] == gamestate[8] or gamestate[2] == gamestate[4] == gamestate[6]:
            winner = 2
            win = True
            return winner, win
    else:
        winner = 'None' 
        win = False
        return winner, win

稍后，当我try 在另一个函数中更改这些值时:

winner, win = check_win(turn, gamestate) <--- Where error was found

以下是完整的代码:

print('Tic Tac Toe:')
pos = 0
turn = 1
gamestate = ['-', '-', '-', '-', '-', '-', '-', '-', '-']

def display_board(gamestate):
    print(gamestate[0:3])
    print(gamestate[3:6])
    print(gamestate[6:9])
def move_validity(pos, gamestate):
    if str(gamestate[int(pos)]) != '-':
        print('Invalid move.')
        valid = False
        return valid
    else:
        valid = True
        return valid
def update(gamestate, pos):
        if turn == 1:
            gamestate[int(pos)] = 'X'
        if turn == 2:
            gamestate[int(pos)] = 'O'
        else:
            print('ERROR')
def check_win(turn, gamestate):
    if turn == 1:
        if gamestate[0] == gamestate[1] == gamestate[2] != '-' or gamestate[3] == gamestate[4] == gamestate[5] != '-' or gamestate[6] == gamestate[7] == gamestate[8] != '-':
            winner = 1
            win = True
            return winner, win
        elif gamestate[0] == gamestate[3] == gamestate[6] != '-' or gamestate[1] == gamestate[4] == gamestate[7] != '-' or gamestate[2] == gamestate[5] == gamestate[8] != '-':
            winner = 1
            win = True
            return winner, win
        elif gamestate[0] == gamestate[4] == gamestate[8] != '-' or gamestate[2] == gamestate[4] == gamestate[6] != '-':
            winner = 1
            win = True
            return winner, win
    elif turn == 2:
        if gamestate[0] == gamestate[1] == gamestate[2] or gamestate[3] == gamestate[4] == gamestate[5] or gamestate[6] == gamestate[7] == gamestate[8]:
            winner = 2
            win = True
            return winner, win
        elif gamestate[0] == gamestate[3] == gamestate[6] or gamestate[1] == gamestate[4] == gamestate[7] or gamestate[2] == gamestate[5] == gamestate[8]:
            winner = 2
            win = True
            return winner, win
        elif gamestate[0] == gamestate[4] == gamestate[8] or gamestate[2] == gamestate[4] == gamestate[6]:
            winner = 2
            win = True
            return winner, win
    else:
        winner = 'None'
        win = False
        return winner, win
def restart():
    gamestate = ['-', '-', '-', '-', '-', '-', '-', '-', '-']
    turn = 1
    win = False
    return gamestate, turn, win
def choose_position():
    pos = input('Player ' + str(turn) + ': ')
    if int(pos) < 0 or int(pos) > 8:
        print('Invalid move')
    else:
        return pos
def Tic_Tac_Toe():
    while True:
        global pos
        global turn
        if turn == 1:
            pos = choose_position()
            valid = move_validity(pos, gamestate)
            if valid == True:
                update(gamestate, pos)
            if valid == False:
                break
            winner, win = check_win(turn, gamestate)
            if win == True:
                print(str(winner) + ' wins!')
                break
            if '-' not in gamestate:
                print('Tie game.')
                break
        if turn == 2:
            pos = choose_position()
            if move_validity(pos, gamestate) == True:
                continue
            if move_validity(pos, gamestate) == False:
                break
            update(gamestate, pos)
            winner, win = check_win(turn, gamestate)
            if win == True:
                print(str(winner) + ' wins!')
                break
            turn = 1
            if '-' not in gamestate:
                print('Tie game.')
                break

        display_board(gamestate)
display_board(gamestate)
Tic_Tac_Toe()
restart_case = input('y/n Would you like to play? ')
if restart_case == 'y':
    gameboard, turn, win = restart()

非常感谢，如果这个解决方案是一个小的拼写错误，那么很抱歉，我对这个问题真的很陌生，在这个问题上花了太多时间D