playlist throwing a server error because of malformed graphql query

[joelhooks]

https://next.egghead.io/playlists/mdx-conf-3fc2

Need to investigate what's missing here. Summary vs description is my gues

RuntimeError: Failed to implement GenericResource.description, tried: - 
`Types::Resources::GenericResource#description`, which did not exist - 
`Lesson#description`, which did not exist - Looking up hash key `:description` 
or `"description"` on `Demystifying MDX`, but it wasn't a Hash To implement 
this field, define one of the methods above (and check for typos)

{
  "query" => "\n query getPlaylist($slug: String!) {\n playlist(slug: $slug)
 {\n slug\n title\n description\n image_thumb_url\n square_cover_480_url\n 
average_rating_out_of_5\n rating_count\n watched_count\n path\n primary_tag {\n 
name\n image_url\n slug\n }\n items {\n ... on 
Course {\n slug\n title\n summary\n description\n path\n square_cover_url\n type\n }\n ... 
on Playlist {\n slug\n title\n description\n path\n square_cover_url\n type\n url\n lessons 
{\n title\n path\n slug\n icon_url\n }\n }\n ... on Lesson {\n slug\n title\n description\n 
path\n http_url\n icon_url\n type\n }\n ... on File {\n slug\n title\n url\n description\n 
square_cover_480_url\n square_cover_url\n type\n }\n ... on Download {\n slug\n title\n url\n 
summary\n description\n square_cover_480_url\n square_cover_url\n type\n }\n ... 
on Url {\n title\n url\n description\n square_cover_480_url\n square_cover_url\n type\n }\n ... 
on GenericResource {\n title\n url\n description\n square_cover_480_url\n 
square_cover_url\n type\n }\n }\n instructor {\n id\n full_name\n slug\n avatar_url\n 
avatar_64_url\n bio_short\n twitter\n }\n owner 
{\n id\n full_name\n avatar_url\n }\n }\n }\n ",
  "variables" => {"slug" => "mdx-conf-3fc2"},
  "controller" => "graphql",
  "action" => "execute",
  "graphql" => {
    "query" => "\n query getPlaylist($slug: String!) {\n playlist(slug: $slug) {\n slug\n 
title\n description\n image_thumb_url\n square_cover_480_url\n average_rating_out_of_5\n
 rating_count\n watched_count\n path\n primary_tag {\n name\n image_url\n slug\n }\n
 items {\n ... on Course {\n slug\n title\n summary\n description\n path\n square_cover_url\n type\n 
}\n ... on Playlist {\n slug\n title\n description\n path\n square_cover_url\n type\n url\n lessons
 {\n title\n path\n slug\n icon_url\n }\n }\n ... on Lesson {\n slug\n title\n description\n path\n 
http_url\n icon_url\n type\n }\n ... on File {\n slug\n title\n url\n description\n
 square_cover_480_url\n square_cover_url\n type\n }\n ... on Download {\n slug\n title\n url\n 
summary\n description\n square_cover_480_url\n square_cover_url\n type\n }\n ... 
on Url {\n title\n url\n description\n square_cover_480_url\n square_cover_url\n type\n }\n ... 
on GenericResource {\n title\n url\n description\n square_cover_480_url\n 
square_cover_url\n type\n }\n }\n instructor {\n id\n full_name\n slug\n avatar_url\n avatar_64_url\n 
bio_short\n twitter\n }\n owner {\n id\n full_name\n avatar_url\n }\n }\n }\n ",
    "variables" => {"slug" => "mdx-conf-3fc2"}
  }
}