async handle(namedParams, queryParams) {
    throw new Error(`Handler not implemented for ${this.constructor.name}`)
  }
Asynchronous function to handle requests for this service. Take the route
parameters (as defined in the `route` property), perform a request using
`this._requestFetcher`, and return the badge data.

@abstract
@param {object} namedParams Params parsed from route pattern
   defined in this.route.pattern or this.route.capture
@param {object} queryParams Params parsed from the query string
@returns {module:core/base-service/base~Badge}
   badge Object validated against serviceDataSchema