I don't see why a response of 0 would give an uninitialized warning.
Are you sure it does? I was going to suggest putting default
responses in the html form to eliminate the warnings, but if
you are getting the response in the way you indicate, default
responses may not fix it.
I'm not sure if this is browser dependant or not, but upon posting a html form with a zero value, I have found many times that the element is not passed through to the script.