Formula works but returns #ERROR on blank cells

I have this formula
WORKDAY({Release Date},-{weeks out in #days})
it returns the date that I need but if there is a cell with Release Date empty, it returns #ERROR.
I have tried this formula
IF( AND( {Release Date}, {weeks out in #days} ), DATETIME_DIFF({weeks out in #days},{Release Date},‘date’), BLANK())
it removes the #ERROR on the cells that it should, but it puts #ERROR in all of the date fields, I lose the dates that I need.
I have tried this formula
WORKDAY({Release Date},-{weeks out in #days}, BLANK())
this one puts #ERROR in all cells.
what I need:
the first formula that returns dates, but if the {Release Date} cell is empty, I want to see a blank rather than #ERROR.