My game is crashing on Quit and my apples is not appearing to screen, can someone point out the errors within my code? 

import pygame
import time
import random


pygame.init() # initalise the pygame module

# here we define some variables with colour codes
white = (255,255,255)
black = (0,0,0)
red = (255,0,0)

display_width = 800  # windows width
display_height = 600  # window height

gameDisplay = pygame.display.set_mode((display_width,display_height)) #returns surface object
pygame.display.set_caption('slither')# sets caption at top of screen


clock = pygame.time.Clock()
font = pygame.font.SysFont(None,50 )  # creates Font object


def message_to_screen(msg,colour):  # prints message to screen for the user
    screen_text = font.render(msg, True, colour)
    gameDisplay.blit(screen_text, [display_width/2,display_height/2])

def gameLoop():

    
    gameExit = False
    gameOver = False
    lead_x = display_width/2 #starting position for snake
    lead_y = display_height/2 # starting position for snake
    lead_x_change = 0
    lead_y_change = 0
    fps = 10  # Screen frames per second rate
    block_size = 10 # size of each snake block
    randAppleX = random.randrange(0,display_width - block_size)
    randAppleY = random.randrange(0,display_width - block_size)

    

    while not gameExit:
        

        while gameOver == True:
            gameDisplay.fill(red)
            pygame.draw.rect(gameDisplay, red, [randAppleX, randAppleY,block_size,block_size])
            
            message_to_screen('Game Over, press C to play again or Q to quit', white)
            pygame.display.update()
            for event in pygame.event.get():
                if event.type == pygame.KEYDOWN:
                    if event.key == pygame.K_q:
                        gameExit = True
                        GameOver = False
                    elif event.key == pygame.K_c:
                        gameLoop()
                    
        for event in pygame.event.get():
            if event.type == pygame.QUIT: # looks for the game QUIT event and takes action
                gameExit = True
            if event.type == pygame.KEYDOWN:  #checks for  KEYDOWN EVENT
                if event.key == pygame.K_LEFT:
                    lead_x_change = -block_size
                    lead_y_change = 0
                elif event.key == pygame.K_RIGHT:
                    lead_x_change = block_size
                    lead_y_change = 0
                elif event.key == pygame.K_UP:
                    lead_y_change = -block_size
                    lead_x_change=0
                elif event.key == pygame.K_DOWN:
                    lead_y_change = block_size
                    lead_x_change=0
                    
        lead_x += lead_x_change
        lead_y += lead_y_change

        if lead_x > display_width or lead_x < 0 or lead_y >display_height or lead_y