public Response setError(Throwable error) {
        this.error = error;
        return this;
    }
<p>Sets the error of this response. It is encouraged, although not enforced, to use this field to attach
additional information to an unsuccessful response.</p>

<p>Because access to this field is not guarded by any lock, any changes made after calling {@link
ResponseHandler#handleResponse(Response)} might never become visible to other threads.</p>

@param error The error to set.
@return This, to allow chaining.
@see #getError()
jdisc_core/src/main/java/com/yahoo/jdisc/Response.java