Scraping a website with missing url / ruby

I am scraping a website and some urls are missing. As a result, my code can't get all the data I'm trying to save.

Here is my code :

informations = []

0.upto(94) do |n|
  begin
    html_file = open(departement[n]).read
    html_doc = Nokogiri::HTML(html_file)
    unless n == 19
      html_doc.search('a').each do |element|
        if n < 9
          x = "http://www.annuaire-des-mairies.com/0#{n + 1}/" + element.text.strip
          informations << x
        elsif n > 9 && n < 19
          y = "http://www.annuaire-des-mairies.com/#{n + 1}/" + element.text.strip
          informations << y
        elsif n > 19
          z=  "http://www.annuaire-des-mairies.com/#{n + 2}/" + element.text.strip
          informations << z

          csv_options = { col_sep: ',', force_quotes: true, quote_char: '"' }
          filepath    = 'mairiesscrapées.csv'
          informations.each do |information|
            next unless information.include? ".html"
            html_file = open(URI.parse(URI.escape(information))).read
            html_doc = Nokogiri::HTML(html_file)
            g = html_doc.search("td")
            CSV.open(filepath, 'ab', csv_options) do |csv|
              csv << [g[0].to_s, g[3].to_s, g[7].to_s, g[13].to_s]
              puts csv
            rescue OpenURI::HTTPError => ex
               puts "Handle missing link here"
            end
          end
        end
      end
    end
  end
end

I've tried to insert a begin rescue method but my console keeps answering me with :

     1: from /Users/pierrelaburthe/.rbenv/versions/2.6.3/lib/ruby/2.6.0/open-uri.rb:756:in `buffer_open'
/Users/pierrelaburthe/.rbenv/versions/2.6.3/lib/ruby/2.6.0/open-uri.rb:378:in `open_http': 404 Not Found (OpenURI::HTTPError)