The Countdown isn't visible and I have an error

Question

My problem is that if I start it the counter isn't visible and if I close the program it gives me the following error:

File "C:\Users\****\AppData\Local\Programs\Python\Python36-32
\lib\tkinter\__init__.py", line 1176, in update_idletasks
    self.tk.call('update', 'idletasks')
_tkinter.TclError: can't invoke "update" command: application has been destroyed

Here is my code:

from tkinter import *
import tkinter.messagebox
fenster = Tk()
tkinter.messagebox.showinfo("", "Willkommen bei wer wird Millionär")#Welcome to  who is Millionaire
answer = tkinter.messagebox.askquestion("", "Möchtest du im Schweren Modus spielen? Der schwere modus bedeutet das du nur 2 Joker hast!")#Do you want to play in Hard mode?if you play in hardmode you only have 2 joker
menu = Menu(fenster)
fenster.config(menu=menu)#window
frage = Label()#question
frage.grid(row=0, column=1)
ausgabe = Label()#output
ausgabe.grid(row=4, column=1)#output
jokerfrage = None
zähler = Label(fg="black")
zähler.grid(row=0, column=0)
x = 0
v = IntVar()

def fiftyfifty():
    subMenu.delete("50/50", index2=None)#Fiftiy fifty Joker

    
def fiftyfifty1():
    subMenu.delete("1.50/50", index2=None)#Fiftiy fifty Joker

    
def fiftyfifty2():
    subMenu.delete("2.50/50", index2=None)#Fiftiy fifty Joker

    
def publikum():
    print("Publikum ist nicht anwesend tut mir leid!")#Sorry there is no people that can help you


def jokerfragen():
    global jokerfrage
    jokerfrage = tkinter.messagebox.askquestion("", "Hör auf nachzudenken und benutz lieber einen Joker!")#Stop thinking use a joker!


def antwortr():
    frage.configure(text="Glückwunsch deine antwort war richtig")#Greetings youre answers whas right
    ausgabe.configure(text="50")
zähler.after(29000, jokerfragen)#which joker he wants


def antwortf():
    frage.configure(text="Deine antwort wahr falsch damit bist du ausgeschieden!")#Sorry youre answer whas wrong you lost the game


def vändern1():
    v = 1
    if v == 1:
        knopf1 = Button(text="Einlocken", command=antwortr)#Lock in
        knopf1.grid(row=3, column=1)


def vändern2():
    v = 2
    if v == 2:
        knopf1 = Button(text="Einlocken",command=antwortf)#Lock in
        knopf1.grid(row=3, column=1)


if answer == "no":
    subMenu = Menu(menu)
    menu.add_cascade(label="Joker", menu=subMenu)
    subMenu.add_command(label="1.50/50", command=fiftyfifty1)#2 wrong question go away
    subMenu.add_command(label="2.50/50", command=fiftyfifty2)#2 wrong question go away
    subMenu.add_separator()
    subMenu.add_command(label="1.Publikum Befragen", command=publikum)#ask other people joker
    subMenu.add_command(label="2.Publikum Befragen", command=publikum)#ask other people joker
    x = x + 1
if answer == "yes":
    subMenu = Menu(menu)
    menu.add_cascade(label="Joker", menu=subMenu)
    subMenu.add_command(label="50/50", command=fiftyfifty)
    subMenu.add_separator()
    subMenu.add_command(label="Publikum Befragen", command=publikum)#ask other people joker
    x = x + 1

# Frage 1
if x == 1:
    frage.configure(text="Wie heist das heilige Buch der Christen?")#What is the Holy book of the Christians
    Radiobutton(fenster, text="Bibel", variable=v, value=1, command=vändern1).grid(row=1, column=0)
    Radiobutton(fenster, text="Thora", variable=v, value=2, command=vändern2).grid(row=1, column=1)
    Radiobutton(fenster, text="Koran", variable=v, value=3, command=vändern2).grid(row=2, column=0)
    Radiobutton(fenster, text="Tipitaka", variable=v, value=4, command=vändern2).grid(row=2, column=1)


def counter_label():
    while True: # keeps looping forever
        for counter in range(30, -1, -1): # loops backwards from 30 up to and including 0
            zähler.config(text = str(counter))
            zähler.after(1000, count)
        sleep(1000)
while jokerfrage is None:
    fenster.mainloop(10)
    fenster.update()
    fenster.update_idletasks()
if jokerfrage == "yes":
    wjokerfrage = tkinter.messagebox.askquestion("", "50/50 ist Ja Publikum Befragen ist nein")#which Joker you want 50/50 is yes ask other people joker is no
if jokerfrage == "no":
    tkinter.messagebox.showinfo("", "Ok ich werde dir weitere 30 sekunden zum nackdenken geben")#ok I'll give you 30 more seconds to think
mainloop()

So that is my whole program, I am new to Python and this is my first "larger" project for School but I have many problems I couldn't correct without you guys.

Answer 1

Here you go. This is a working code for your program. The issue as I stated in my previous comment was that you never called your function in the first place. so you never actually had counter_label().

def counter_label(count):        
    label['text'] = count

    if count > 0:
        fenster.after(1000, counter_label, count-1)
    else:
        dostuff()

label = Label(fenster)
label.grid()
counter_label(30)

def dostuff():
    print("hi")