ошибка: NoMethodError: undefined method `each' for nil:NilClass

seeds.rb

require "nokogiri"
require "open-uri"

page = Nokogiri::HTML(open("http://lingvotutor.ru/1500-samyx-upotreblyaemyx-slov-k-toefl"))

word_list = []

page.search("table.tablepress tablepress-id-579")[0].each do |row|
  original = row.css('th.column-1')[0].text
  translated = row.css('th.column-3')[0].text
  word_list << Hash[original, translated]
end