Well, I've fixed the main part - if you try to enter a closing time of "0 <unit>", it will error. Additionally, I've changed it so that you can enter partial units. 0.5 hours was cast to an integer, meaning 0 hours.
I should note that you have to enter "0.5" though (not 0,5). Parsing expects a dot for the decimal point (rather standard across most programming languages).