Angular 2: custom error message from the server

[Eric Blankenburg]

How do I get a custom error message from the server?

        this.subscriberService

            .listSubscriberTypes()

            .subscribe(subscriberTypes => this.subscriberTypes = subscriberTypes, 

                        error => this.handleError(error));

error is just a string that describes the http error.

I want something more descriptive for the user.