Does the sitemap really need to include 404 error?

_config.yml

@@ -29,6 +29,7 @@ sitemap:
     exclude:
         # Even if you can see the existence of these pages here, I don't
         # wish to get search engine attention to them.
+        - "/404.html"
         - "/bot.html"
         - "/channel.html"
 include: [PGP, PHP, keybase.txt, robots.txt]

robots.txt

@@ -3,6 +3,7 @@ Allow: /
 
 # I prefer search engines to not advertise these pages even if you can find
 # them here or in `_config.yml`.
+Deny: /404.html
 Deny: /bot.html
 Deny: /channel.html