if you have messege error like this (screenshot), you need a change line "
levelimages.append(pygame.transform.scale(pygame.image.load("./images/maps/"+str(i+1)+".png"), [185, 137]))"
to "
levelimages.append(pygame.transform.scale(pygame.image.load("./images/maps/"+str(i+1)+".PNG"), [185, 137]))"