return size of 0 if json ruby value is nil

An entry can be null such as [null], which is 1 entry. If a null is a value of an Array, then the array has 0 entry.  However a null value returns a size of 1

def matches?(json)
       ruby = parse_json(json, @path)
      #when ruby = nil 
      #NoMethodError: undefined method `size' for nil:NilClass
      # so @actual = 1 when ruby is nil
     @actual = Enumerable === ruby ? ruby.size : 1
      @actual == @expected
  end
I'm saying that the existing functionality is wrong. If what json_spec finds is not an enumerable, we should blow up immediately. It's not worth comparing size when we're dealing with values that are neither hashes nor arrays.