Hey @miyazato @Fares I ran into this problem and I solved it.
For context, I am also using prismic-ts-codegen
and a GraphQuery.
I looked at the isFilled.contentRelationship
and noticed it accepted some generic type arguments, and this is working for me:
// contentRelationship: <TypeEnum, LangEnum, DataInterface>
if (isFilled.contentRelationship<'blog-author', string, BlogAuthorDocument['data']>(doc.data.authorLink)) {
doc.data.authorLink.data?.avatar;
}