lua (love2d): function supposedly missing an end

它说第 98 行的函数缺少一个 end。我发誓没有缺少 end，我一遍一遍地检查，也找不到问题所在。

错误

语法错误：main.lua:142: 需要 'end'（在第 98 行关闭 'function'）附近''

回溯

[C] 中的 0x07f9a11328f0 中的 'require' 函数 [C] 中的 'xpcall' 函数 [C] 中的 'xpcall' 函数

player = {}
opponent = {}
ball = {}
screen ={}

function love.load()

    screen.top = 0
    screen.bottom = love.graphics.getHeight()
    screen.left = 0
    screen.right = love.graphics.getWidth()

    player.x = 50
    player.y = screen.bottom / 2
    player.width = 20
    player.height = 100
    player.speed = 500

    opponent.x = screen.right - 50
    opponent.y = screen.bottom / 2
    opponent.width = 20
    opponent.height = 100
    opponent.speed = 400

    ball.x = screen.right / 2 - 10
    ball.y = screen.bottom / 2 - 10
    ball.width = 20
    ball.height = 20
    ball.speed = 200
    ball.xVel = -ball.speed
    ball.yVel = 0

end

function love.update(dt)

    player.move(dt)

    opponent.move(dt)

    ball.move(dt)
    ball.collide(dt)

end

function love.draw(dt)

    player.draw()

    opponent.draw()

    ball.draw()

end

function checkCollision(a, b)

    if a.x + a.width > b.x and a.x < b.x + b.width and a.y + a.height > b.y and a.y < b.y + b.height then
        return true
    else
        return false
    end

end

function player.draw()

    love.graphics.rectangle('fill', player.x, player.y, player.width, player.height)

end
function player.move(dt)

    if love.keyboard.isDown('w') then
        player.y = player.y - player.speed * dt
    elseif love.keyboard.isDown('s') then
        player.y = player.y + player.speed * dt
    end

    if player.y < screen.top then
        player.y = screen.top
    elseif player.y + player.height > screen.bottom then
        player.y = screen.bottom - player.height
    end

end

function opponent.draw()

    love.graphics.rectangle('fill', opponent.x, opponent.y, opponent.width, opponent.height)

end
function opponent.move(dt)

    if ball.y + ball.height < opponent.y then
        opponent.y = opponent.y - opponent.speed
    else if ball.y > opponent.y + opponent.height then
        opponent.y = opponent.y + opponent.speed
    end

    if opponent.y < screen.top then
        opponent.y = screen.top
    elseif opponent.y + opponent.height > screen.bottom then
        opponent.y = screen.bottom - opponent.height
    end

end

function ball.draw()

    love.graphics.rectangle('fill', ball.x, ball.y, ball.width, ball.height)

end
function ball.move(dt)

    ball.x = ball.x + ball.xVel * dt
    ball.y = ball.y + ball.yVel * dt

    if ball.y < screen.top then
        ball.y = screen.top
        ball.yVel = -ball.yVel
    elseif ball.y + ball.height > screen.bottom then
        ball.y = screen.bottom
        ball.yVel = -ball.yVel
    end
end
function ball.collide(dt)

    if checkCollision(ball, player) then
        ball.xVel = -ball.xVel
        local middleBall = ball.y + (ball.height / 2)
        local middlePlayer = player.y + (player.height / 2)
        local collisionPosition = middleBall - middlePlayer
        ball.yVel = collisionPosition
    end
end