Veneer Project - self.owner.name and self.owner.location is throwing an error

I know this is a walkthrough project but I did it without seeing and am getting errors. After seeing the walkthrough also I cannot figure out what has gone wrong. Can someone help me out?

class Art:
  def __init__(self, artist, title, year,medium, owner):
    self.artist = artist
    self.title = title
    self.medium = medium
    self.year = year
    self.owner = owner

  def __repr__(self):
    return "{}. \"{}\". {}, {}. {}, {}".format(self.artist, self.title, self.year, self.medium, self.owner.name, self.owner.location)


class Marketplace:
  def __init__(self):
    self.listings = []

  def add_listing(self, new_listing):
    self.listings.append(new_listing)

  def remove_listing(self, listing):
    self.listings.remove(listing)

  def show_listings(self):
    for i in self.listings:
      print(i)


class Client:
  def __init__(self, name, location, is_museum):
    self.name = name
    self.is_museum = is_museum
    if is_museum:
      self.location = location
    else:
      self.location = "Private Collection"

  def sell_artwork(self, artwork, price):
    if artwork.owner == self:
      new_listing = Listing(artwork, price, self)
      veneer.add_listing(new_listing)

  def buy_artwork(self, artwork):
    if artwork.owner != self:
      art_listing = None
      for listing in veneer.listings:
        if listing.art == artwork:
          art_listing = listing
          break
      if art_listing != None:
        art_listing.art.owner = self.name
        veneer.remove_listing(art_listing)


class Listing:
  def __init__(self, art, price, seller):
    self.art = art
    self.price = price
    self.seller = seller

  def __repr__(self):
    return "{}, {}.".format(self.art.title, self.price)


veneer = Marketplace()

edytta = Client("Edytta Halpirt", None, False)

moma = Client("The MOMA", "New York", True)

girl_with_mandolin = Art("Picasso, Pablo", "Girl with a Mandolin(Fanny Tellier", 1910, "oil on canvas", edytta)
#print(girl_with_mandolin)

edytta.sell_artwork(girl_with_mandolin, "6M(USD")

#veneer.show_listings()

moma.buy_artwork(girl_with_mandolin)
print(girl_with_mandolin)

2 posts were merged into an existing topic: Question in the “Veneer” Project in Python