Episode canonical title is not nullable in GraphQL

[ariesclark]

This issue is causing me a fair bit of problems when querying for episodes.

[mizaki]

This is the same with manga and chapters. Example:

query chaptersByMangaId ($id: ID!, $limit: Int, $after: String) {
    findMangaById(id: $id) {
        chapters (first: $limit, after: $after) {
            nodes {
                id
                titles {
                  canonical
                }
            }
        }
    }
}

{"id": 35, "limit": 1, "after": ""}

{
  "data": {
    "findMangaById": {
      "chapters": {
        "nodes": [
          null
        ]
      }
    }
  },
  "errors": [
    {
      "message": "Cannot return null for non-nullable field TitlesList.canonical"
    }
  ]
}

Using preferred also causes "error": "JSON.parse: unexpected character at line 1 column 1 of the JSON data"