[Python] My Tron-Like game makes the turtles randomly stop

When launched my game runs fine, there are 2 massive issues though; I can't seem to get my collision detection to work, and both my turtles randomly stop! I am using Repl.it

I have tried moving pieces of code, I have tried reworking parts of it to coordinates opposed to forward/back, and i have tried making my list update without a timer but that resulted in heavy lag

from turtle import Screen, Turtle
import sys
import time
fps = 2
# preGame setup
player1 = Turtle()
player1.hideturtle()
player1.up()
player1.goto(0, 350)
player1.down()
player1.right(90)
player1.color('red')
player1.speed(5)
player1.showturtle()

def r1():
player1.left(90)

def l1():
player1.right(90)

player2 = Turtle()
player2.hideturtle()
player2.up()
player2.goto(0, -350)
player2.down()
player2.left(90)
player2.color('blue')
player2.speed(5)
player2.showturtle()
players = player1, player2
def r2():
player2.right(90)

def l2():
player2.left(90)

# main game loop

def move():
player1.forward(5)

if not (-350 < player1.xcor() < 350 and -350 < player1.ycor() < 350):
player1.backward(30)

player2.forward(5)

if not (-350 < player2.xcor() < 350 and -350 < player2.ycor() < 350):
player2.backward(30)

if player1.distance(player2) < 5:
print("DON'T CRASH INTO THE OTHER PLAYER!")
sys.exit()
screen.ontimer(move, 5)
L = list()
l = list()
l.append(player1.pos())
L.append(player1.pos())
while True:
l.extend(player1.pos())
L.extend(player2.pos())
time.sleep(.5)
if player1.distance(L) < 5:
print('player 2 wins!!')
sys.exit()
if player2.distance(l) < 5:
print('player 1 wins!!')
sys.exit()
break

screen = Screen()

screen.onkey(r1, 'd')
screen.onkey(l1, 'a')
screen.onkey(r2, 'left')
screen.onkey(l2, 'right')

screen.listen()

move()

screen.mainloop()


I expect both of the turtles to move indefinitely until one collides with another, but one always stops or both stop.

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