How to raise a message box in case of not handled Error in Python?

I have a huge in size Python script which takes much time for its execution, runs in background and is started in a way that I can't see its printing output.

In order to to be able to get notified when the script is finished I raise an appropriate message box, but if the script exits because of an Error I won't get notified.

Below a minimal code demonstrating what I am speaking about:

import math
try: 
    i = int('Oxff') 
except ValueError:
      ...             # some code handling the exception  
... ; pass ; ...      # some further code  
import no_such_module # in code not handled unexpected error 
... ; pass ; ...      # some further code  
# Message box notifying about successfull script run: 
from tkinter import Tk
root = Tk()
root.geometry('10x10+'+str(root.winfo_screenwidth()-10)+'+'+str(root.winfo_screenheight()-10))
from tkinter.messagebox import Message 
Message(title="Success", message="No Error", master=root).show()

So when my Python script fails due to an unexpected and therefore not in code handled error I will not get notified at all.

I don't want to enclose the entire script code with try: ... except: ... in order to handle unexpected and in code not handled errors.

Is there in Python a way to write a function which will be run displaying a message box in case an unexpected error terminates the script?