Mapped types are dropped when combined with unions at non-trivial depth.

Issue workflow progress

Progress of the issue based on the Contributor Workflow

• 1. The issue provides a reproduction available on Github, Stackblitz or CodeSandbox

Make sure to fork this template and run yarn generate in the terminal.

Please make sure the Codegen and plugins version under package.json matches yours.

• 2. A failing test has been provided

• 3. A local solution has been provided

• 4. A pull request is pending review

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Describe the bug The resolver type for a type that contains a type that contains a union of types that are mapped, drops knowledge of the mapped type.

That a mouthful, but here is a minimal reproduction:

To Reproduce LIve Code Sandbox: https://codesandbox.io/s/inspiring-shape-ts0t5

1. My GraphQL schema:

type Query {
    feed: FeedConnection!
}

type FeedConnection {
    edge:FeedEdge
}

type FeedEdge {
    node: FeedNode
}

union FeedNode = PostFeedNode | PhotoFeedNode

type PostFeedNode {
    text:String
}

type PhotoFeedNode {
    url:String
}

2. My GraphQL operations: N/A

3. My codegen.yml config file:

schema: schema.graphql
generates:
  types.ts:
    plugins:
      - typescript
      - typescript-resolvers
    config:
      mappers:
        PostFeedNode: ./model#PostFeedNodeModel
        PhotoFeedNode: ./model#PhotoFeedNodeModel

Expected behavior The resolver type should be: FeedConnection:ResolverTypeWrapper<Omit<FeedConnection, 'edge'> & { node?: Maybe<ResolversTypes['FeedEdge']> }>;

But the generated type is: FeedConnection: ResolverTypeWrapper<FeedConnection>;