graphql-modules + typegraphql + graphql-apollo-server example

simple GraphQL-Apollo-Server example demonstrate a bug when using unions in combination with graphql-modules + typegraphql + apollo-server. would like to know how to solve this problem or how to debug it.

commands to reproduce the issue:

git clone [email protected]:devtim123/graphql-modules-union-example.git
cd graphql-modules-union-example
yarn install
yarn dev

and visit http://localhost:4000/api

start query at playground:

query example {
  example {
    __typename
    ... on Actor {
      name
      age
    }
    ... on Movie {
      name
      rating
    }
  }
}

expected result:

{
  "data": {
    "example": {
      "__typename": "Movie",
      "name": "Fight Club",
      "rating": 999
    }
  }
}

current result:

{
  "data": {
    "example": {
      "__typename": "Movie"
    }
  }
}

For this simple example, creating the schema via (see Line #15 @ src/server.ts), the resolver works as expected:

const schema = await buildSchema({
    resolvers: [rootModule.resolvers]
});

But this works not in larger GraphQL-Modules projects, where i get the following error on startup:

TypeError: Cannot convert undefined or null to object

This Repo is linked in the issue: Urigo/graphql-modules#619

I hope we can find a solution there...