Python NonType error

Hello everyone, I’m using slots to save a number and then convert it to an int so i can use it later, I tried the slot type type text and the slot type float but i always get the same error : int() argument must be a string, a bytes-like object or a number, not ‘NoneType’ My domain.yml image My image My image

NoneType means that the slot isn’t being filled. How do you extract that entity?