The problem

• I have a 1-1 relation between Author and Book.
• A book has an author, and it is the owning side of the relation.
• An author can have a book, but it is not required.
• When I try to load a book from an author, I get the following error:

const book = await author.book.load(); // Error: Cannot read properties of undefined (reading 'load')

I expect it to return null if the author does not have a book.

Steps to reproduce

1. Run pnpm start:dev in the root
2. Access the GraphQL playground at http://localhost:3000/graphql
3. Create an author and book in the GraphQL playground:

mutation create {
  createAuthor {
    id
    name
  }
}

Copy the author ID and query the author:

{
  findAuthor(id: "YOUR_ID") {
    id
    name
  }
}

This also tries to load the book from the author, but it will fail. You'll get the error:

TypeError: Cannot read properties of undefined (reading 'load')

However we can load the book from the BookRepository, and we can do book.author.load() without any issues.