Since the GraphQLError extends JavaScripts Error class anywhere that we can use a JavaScript error (typed in ReScript as Js.Exn.t) we can also use a GraphQLError.
Error reporting code that accepts a Js.Exn.t can't directly accept a GraphQLError. Adding an asJsExn method to GraphQLError.res could simplify code that deals with errors :) external asJsExn : t => Js.Exn.t = "%identity" should probably do the trick :D (this only holds from GraphQLError -> Error)