IFS and IFError nesting

I am trying to nest formulas and cant seem to resolve my issue with solutions from other postings. I would like my formula to search a cell and if blank, return a blank...if the referenced cell has a number, return an "iferror" result

For example in the below I would like cell "W2" to return a blank as "S2" is blank. If "S2" were to have any numeric value, it would populate the calculated variance in "W2" (i.e. =IFERROR((P51-P50)/P50,0))

Thanks so much in advance!