Last day(s) selection #34

Hi.

I found a problem, when you select Date Range: Last day(s), and appears the input box to select the number of days you want, the calendar doesn't do anything, with or without compare to and if you click apply if you want to open again the DatePicker it w0n't open, you have to refresh the page.

How and where can i do the checking of dates if instead of a valid date it's inserted '0' ?
what i'm saying is in the date range, if selected custom and inserted 0 as dates it will accept.

thk