Ошибка при попытке уничтожения окна

from tkinter import *
y = 0
root = Tk()
root.title("CS.FAIL.org")
root.geometry("1080x640")
def createNewWindow():
    newWindow = Toplevel(root)
    labelExample = Label(newWindow, text = "New Window")
    buttonExample = Button(newWindow, text = "New Window button")
    global y
    y = y + 1
    if y == 2:
        y = 0
        newWindow.destroy()
 
    labelExample.place(x=0,y=0)
    buttonExample.place(x= 10,y= 40)
def commanda():
    ent.place_forget()
    btnn2.place_forget()
    global lbl
    label = ent.get()
    lbl = Label(text = label)
    lbl.place(x=0,y=0)
    lbl3.place(x=105,y = 10)
    btnn3.place(x = 130,y = 10)
def reveal():
    ent.place(x=0,y=0)
    btnn2.place(x = 100,y=20)
    lbl.place_forget()
    lbl3.place(x=125,y = 10)
    btnn3.place(x = 150,y = 10)
 
balance = 0
btnn3 = Button(text = "Пополнить������",command = createNewWindow)
btnn3.place(x = 150,y = 10)
lbl3 = Label(text = str(balance) + " р")
lbl3.place(x=125,y = 10)
lbl2 = Label(text = "������")
lbl2.place(x = 1060,y = 0)
btnn = Button(text = "Ввести никнейм",command = reveal)
btnn.place(x=0,y=20)
btnn2 = Button(text = "✓",command = commanda)
ent = Entry()
root.mainloop()