There is no way at present to do that. There have been similar queries previously too. The problem with this is that different APIs return errors in innumerously different ways, and we don’t know apriori that what is the error format an API is going to return. Some, just work with HTTP status codes, some give errors in body directly as string, some give errors as JSON, and what not.
But, can you give us an example of how your API returns errors and how you would want to see that in GraphQL response? That would help us jot down all possible ways of returning errors from APIs, and maybe in future we will try to support the one, which we find to be used by a lot of people.
++ @JatinDevDG