Realm Custom Resolver

I wrote custom resolver whose output payload is a list of an existing schema. The custom returns an array which I checked in the logs and on using this custom resolver in graphiql, it works perfectly.
The problem arises when I call this revolver on my client app using Apollo. I get the following error:

   Error: User Error: expected iterable, but did not find one for field Query.fetchSecondaryBusinessAccounts.
    at new ApolloError (index.ts:49)
    at QueryData._this.getQueryResult (QueryData.ts:366)
    at QueryData.getExecuteResult (QueryData.ts:151)