iDaysInMonth() gives number of days as 1 for some month of a year

[natashajaved]

I am trying to find number of days in a hijri year, for that I'm looping over days in months and found strange case that for 1 month of the year the number of days returned is 1.

Please observe the attached images.
This is an urgent issue. I have chosen this library and started it's implementation. this case is disrupting a major flow.

This is for timezone America/New_York and I'm using moment-timezone for setting zones