I don't think it's a but probably something I don't know how to implement.
The following input field doesn't allow numbers start with 0, but it can be beat by typing e.g. 10 or 20 or 100 or 2390. The important thing is that the number ends with 0, and the user can delete all the numbers before getting 0.
Is there a way do avoid that? For example, when the remaining number is 0, it doesn't allow delete it.