Field counts doesn't trigger error for jobs with lots of NaN

[manycoding]

ghat = Gatf(source='364692/1/17', 
            schema='schemas/Global Strategies/amazon_product.json',
            target='364692/1/14',
#             schema=schema
           )

The price fields here differ on 15% and yet no error in log. Perhaps we don't really want to see an improved coverage?

[manycoding]

@Alexandr1988 What do you think?