handleInitResponse_(paramHash, event) {
    const client = /** @type {XMLHttpRequest} */ (event.target);
    // status will be 0 for file:// urls
    if (!client.status || (client.status >= 200 && client.status < 300)) {
      let response;
      try {
        response = /** @type {CartoDBLayerInfo} */ (
          JSON.parse(client.responseText)
        );
      } catch {
        this.setState('error');
        return;
      }
      this.applyTemplate_(response);
      this.templateCache_[paramHash] = response;
      this.setState('ready');
    } else {
      this.setState('error');
    }
  }
Handle map initialization response.
@param {string} paramHash a hash representing the parameter set that was used
    for the request
@param {Event} event Event.
@private