library not initialized (pygame)

[Quentin Bock]

Code:
#imports and variables for game
import pygame
from pygame import mixer
running = True

#initializes pygame
pygame.init()

#creates the pygame window
screen = pygame.display.set_mode((1200, 800))

#Title and Icon of window
pygame.display.set_caption("3.02 Project")
icon = pygame.image.load('3.02 icon.png')
pygame.display.set_icon(icon)

#setting up font
pygame.font.init()
font = pygame.font.Font('C:\Windows\Fonts\OCRAEXT.ttf', 16)
font_x = 10
font_y = 40
items_picked_up = 0
items_left = 3

def main():
    global running, event

    #Game Loop
    while running:
        #sets screen color to black
        screen.fill((0, 0, 0))

        #checks if the user exits the window
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                running = False
                pygame.quit()

        def display_instruction(x, y):
            instructions = font.render("Each level contains 3 items you
must pick up in each room.", True, (255, 255, 255))
            instructions_2 = font.render("When you have picked up 3 items,
you will advance to the next room, there are 3.", True, (255, 255, 255))
            instructions_3 = font.render("You will be able to change the
direction you are looking in the room, this allows you to find different
objects.", True, (255, 255, 255))
            clear = font.render("Click to clear the text.", True, (255,
255, 255))
            screen.blit(instructions, (10, 40))
            screen.blit(instructions_2, (10, 60))
            screen.blit(instructions_3, (10, 80))
            screen.blit(clear, (10, 120))

        if event.type == pygame.MOUSEBUTTONDOWN:
            if event.type == pygame.MOUSEBUTTONUP:
                screen.fill(pygame.Color('black'))  # clears the screen text

        display_instruction(font_x, font_y)
        pygame.display.update()


main()

the error apparently comes from the first instructions variable saying
library not initialized not sure why, its worked before but not now :/