똑같이 따라 쳤는데 오류가 생겨요

나도코딩님처럼 똑같이 쳤는데 NameError: name 'ball_to_remove' is not defined 이런 오류가 떠여 도와주세요 ㅠㅠ
import os
import pygame
#########################################################
# 기본 초기화 (반드시 해야 하는 것들)
pygame.init() # 초기화 (반드시 필요)

# 화면 크기 설정
screen_width = 640 # 가로 크기
screen_height = 480 # 세로 크기
screen = pygame.display.set_mode((screen_width, screen_height))

# 화면 타이틀 설정
pygame.display.set_caption("서준이의 게임2") #게임 이름

# FPS
clock = pygame.time.Clock()
#########################################################

# 1. 사용자 게임 초기화 (배경 화면, 게임 이미지, 좌표, 속도, 폰트 등)
current_path = os.path.dirname(__file__) # 현재 파일의 위치 반환
image_path = os.path.join(current_path, "images") # images 폴더 위치 반환

# 배경 만들기
background = pygame.image.load(os.path.join(image_path, "background.png"))

# 스테이지 만들기
stage = pygame.image.load(os.path.join(image_path, "stage.png"))
stage_size = stage.get_rect().size
stage_height = stage_size[1] # 스테이지의 높이 위에 캐릭터를 두기 위해 사용

# 캐릭터 만들기
character = pygame.image.load(os.path.join(image_path, "character.png"))
character_size = character.get_rect().size
character_width = character_size[0]
character_height = character_size[1]
character_x_pos =(screen_width /2) - (character_width /2)
character_y_pos = screen_height - character_height - stage_height

# 캐릭터 이동 방향
character_to_x = 0

# 캐릭터 이동 속도
character_speed = 5

# 무기 만들기
weapon = pygame.image.load(os.path.join(image_path, "weapon.png"))
weapon_size = weapon.get_rect().size
weapon_width = weapon_size[0]

# 무기는 한 번에 여러 발 발사 가능
weapons = []

# 무기 이동 속도
weapon_speed = 10

# 공 만들기 (4개 크기에 대해 따로 처리)
ball_images = [
    pygame.image.load(os.path.join(image_path, "balloon1.png")),
    pygame.image.load(os.path.join(image_path, "balloon2.png")),
    pygame.image.load(os.path.join(image_path, "balloon3.png")),
    pygame.image.load(os.path.join(image_path, "balloon4.png"))]

# 공 크기에 따른 최초 스피드
ball_speed_y = [-18, -15, -12, -9] # index 0, 1, 2, 3 에 해당하는 값

# 공들
balls= []

# 최초 발생하는 큰 공 추가
balls.append({
    "pos_x" : 50, # 공의 x 좌표
    "pos_y" : 50, # 공의 y 좌표
    "img_idx" : 0, # 공의 이미지 인덱스
    "to_x": 3, # x축 이동방향, -3 이면 왼쪽으로, 3 이면 오른쪽으로
    "to_y": -6, # y축 이동방향,
    "init_spd_y": ball_speed_y[0]})# y 최초 속도

# 사라질 무기, 공 정보 저장 변수
weapon_to_remove = -1
ball_to_remvoe = -1

running = True
while running:
    dt = clock.tick(60) 

    # 2. 이벤트 처리 (키보드, 마우스 등)
    for event in pygame.event.get():
        if event.type == pygame.QUIT: 
            running = False 

        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_LEFT: # 캐릭터를 왼쪽으로
                character_to_x -= character_speed
            elif event.key == pygame.K_RIGHT: # 캐릭터를 오른쪽으로
                character_to_x += character_speed
            elif event.key == pygame.K_SPACE: # 무기 발사
                weapon_x_pos = character_x_pos + (character_width / 2) - (weapon_width / 2)
                weapon_y_pos = character_y_pos 
                weapons.append([weapon_x_pos, weapon_y_pos])

        if event.type == pygame.KEYUP:
            if event.key == pygame.K_LEFT or event.key == pygame.K_RIGHT:
                character_to_x = 0

    # 3. 게임 캐릭터 위치 정의
    character_x_pos += character_to_x

    if character_x_pos < 0:
        character_x_pos = 0
    elif character_x_pos > screen_width - character_width:
        character_x_pos = screen_width - character_width

    # 무기 위치 조정
    # 100, 200 -> 180, 160, 140, ...
    # 500, 200 -> 180, 160, 140, ...
    weapons = [ [w[0], w[1] - weapon_speed] for w in weapons] # 무기 위치를 위로

    # 천장에 닿은 무기 없애기
    weapons = [ [w[0], w[1]] for w in weapons if w[1] > 0]

    # 공 위치 정의
    for ball_idx, ball_val in enumerate(balls):
        ball_pos_x = ball_val["pos_x"]
        ball_pos_y = ball_val["pos_y"]
        ball_img_idx = ball_val["img_idx"]

        ball_size = ball_images[ball_img_idx].get_rect().size
        ball_width = ball_size[0]
        ball_height = ball_size[1]

        # 가로벽에 닿았을 때 공 이동 위치 변경 (튕겨 나오는 효과)
        if ball_pos_x < 0 or ball_pos_x > screen_width - ball_width:
            ball_val["to_x"] = ball_val["to_x"] * -1

        # 세로 위치
        # 스테이지에 튕겨서 올라가는 처리
        if ball_pos_y >= screen_height - stage_height - ball_height:
            ball_val["to_y"] = ball_val["init_spd_y"]
        else: # 그 외의 모든 경우에는 속도를 증가
            ball_val["to_y"] += 0.5

        ball_val["pos_x"] += ball_val["to_x"]
        ball_val["pos_y"] += ball_val["to_y"]

    # 4. 충돌 처리

    # 캐릭터 rect 정보 업데이트
    character_rect = character.get_rect()
    character_rect.left = character_x_pos
    character_rect.top = character_y_pos

    for ball_idx, ball_val in enumerate(balls):
        ball_pos_x = ball_val["pos_x"]
        ball_pos_y = ball_val["pos_y"]
        ball_img_idx = ball_val["img_idx"]

        # 공 rect 정보 업데이트
        ball_rect = ball_images[ball_img_idx].get_rect()
        ball_rect.left = ball_pos_x
        ball_rect.top = ball_pos_y

        # 공과 캐릭터 충돌 처리
        if character_rect.colliderect(ball_rect):
            running = False
            break

        # 공과 무기들 충돌 처리
        for weapon_idx, weapon_val in enumerate(weapons):
            weapon_pos_x = weapon_val[0]
            weapon_pos_y = weapon_val[1]

            # 무기 rect 정보 업데이트
            weapon_rect = weapon.get_rect()
            weapon_rect.left = weapon_pos_x
            weapon_rect.top = weapon_pos_y

            # 충돌 체크
            if weapon_rect.colliderect(ball_rect):
                weapon_to_remove = weapon_idx # 해당 무기 없애기 위한 값 설정
                ball_to_remove = ball_idx # 해당 공 없애기 위한 값 설정
                break

    # 충돌된 공 or 무기 없애기
    if ball_to_remove > -1:
        del balls[ball_to_remove]
        ball_to_remove = -1


    if weapon_to_remove > -1:
        del weapons[weapon_to_remove]
        weapon_to_remove = -1


    # 5. 화면에 그리기
    screen.blit(background, (0, 0))

    for weapon_x_pos, weapon_y_pos in weapons:
        screen.blit(weapon, (weapon_x_pos, weapon_y_pos))

    for idx,val in enumerate(balls):
        ball_pos_x = val["pos_x"]
        ball_pos_y = val["pos_y"]
        ball_img_idx = val["img_idx"]
        screen.blit(ball_images[ball_img_idx], (ball_pos_x, ball_pos_y))

    screen.blit(stage, (0, screen_height - stage_height))
    screen.blit(character, (character_x_pos, character_y_pos))


    pygame.display.update() 

pygame.quit()
인프런 커뮤니티 질문&답변
