Multiple unexpected errors
<p>I'm not entirely sure what is wrong with these line, I don't understand why they are problematic. In the order of the problems (failing line will be highlighted with ***)</p>

<p>File "C:\Users\Harry\Desktop\CS Project\game test", line 32, in drawArena
    pygame.draw.line(DISPLAYSURF, WHITE, ((WINDOWWIDTH/2),0),((WINDOWWIDTH/2),WINDOWHEIGHT), (LINETHICKNESS/4))
TypeError: integer argument expected, got float</p>

<p>File "C:\Users\Harry\Desktop\CS Project\game test", line 144, in main
    drawArena()</p>

<p>File "C:\Users\Harry\Desktop\CS Project\game test", line 178, in 
    main()</p>

<pre><code>def drawArena():
    DISPLAYSURF.fill((0,0,0))
    #Draw outline of arena
    pygame.draw.rect(DISPLAYSURF, WHITE, ((0,0),(WINDOWWIDTH,WINDOWHEIGHT)), LINETHICKNESS*2)
    #Draw centre line
    ***pygame.draw.line(DISPLAYSURF, WHITE, ((WINDOWWIDTH/2),0),((WINDOWWIDTH/2),WINDOWHEIGHT), (LINETHICKNESS/4))***

***drawArena()***
drawPaddle(paddle1)
drawPaddle(paddle2)
drawBall(ball)

if __name__ == '__main__':
    ***main()***
</code></pre>

<p>It's telling you the error. When using the method <code>pygame.draw.line()</code>, you must provide integer arguments for the dimensions of the line. If you look at your problematic line:</p>

<p><code>pygame.draw.line(DISPLAYSURF, WHITE, ((WINDOWWIDTH/2),0),((WINDOWWIDTH/2),WINDOWHEIGHT), (LINETHICKNESS/4))</code></p>

<p>One or more of the quotients of those division operations are resulting in a float(decimal) number. One simple way to fix this is to use the Python <code>int()</code> function to round any of your decimals to a whole number, like so:</p>

<p><code>pygame.draw.line(int((WINDOWWIDTH/2)),0),(int((WINDOWWIDTH/2)),WINDOWHEIGHT), int((LINETHICKNESS/4)))</code></p>

<p>If int, for some reason is not suitable, you can also use the Python <code>round()</code> function:</p>

<p><code>pygame.draw.line(round((WINDOWWIDTH/2)),0),(round((WINDOWWIDTH/2)),WINDOWHEIGHT), round((LINETHICKNESS/4)))</code></p>

python python-3.x