Subscriptions not working if using RenameRootFields

[maxpain]

Subscriptions not working if using RenameRootFields and schema stiching.
Example:

export default function makeHttpAndWsLink(uri, headers) {
	const httpLink = new HttpLink({ uri, fetch, headers })

	const wsLink = new WebSocketLink(
		new SubscriptionClient(uri, {
			reconnect: true,
			connectionParams: { headers }
		}, ws)
	)

	return split(isSubscription, wsLink, httpLink)
}

export default async function getSchema(): Promise<GraphQLSchema> {
	const link = makeHttpAndWsLink(HASURA_GRAPHQL_ENGINE_URL, { 'x-hasura-access-key': HASURA_ACCESS_KEY })
	const schema = await introspectSchema(link)
	const executableSchema = makeRemoteExecutableSchema({ schema, link })

	return transformSchema(executableSchema, [
		new RenameRootFields((operation, name, field) => 'hasura_' + name)
	])
}

GraphQL subscription:

subscription {
  hasura_games(limit: 1) {
    id
  }
}

An error:

{
  "errors": [
    {
      "message": "Cannot return null for non-nullable field subscription_root.hasura_games.",
      "locations": [
        {
          "line": 2,
          "column": 3
        }
      ],
      "path": [
        "hasura_games"
      ]
    }
  ]
}

ardatan/graphql-tools#997
hasura/graphql-engine#987

[nerdophile]

How did you solve it

[maxpain]

@venkyyPoojari I just not use RenameRootFields :D