How to avoid "can be undefined" error in Python?

I am trying to make a simple code to input a positive integer in the most accurate way possible. I mention that I am very new to the language.

Here is my code :

while number != None:
    try:
        while True:
            number = int(input("Donnez la longueur de votre liste: "))
            if number > 0:
                break
    except TypeError:
        print("Tu doit donner un nombre entier")

The warning I get is number can be Undefined I am not aware of what is the specific situation where number is undefined as the while loop breaks only when number is not None ( means defined according to me ). I’m so grateful for your help. It is a challenging time but you would make it easier.

>Solution :

You can sidestep any warnings with a more idiomatic loop:

while True:
    number = input("Donnez la longueur de votre liste: ")
    try:
        number = int(number)
    except ValueError:
        print("Tu doit donner un nombre entier")
        continue
    
    if number > 0:
        break