copyObjToInstance(obj, type) {
    for (const key in obj) {
      if (typeof this[key] !== 'undefined') {
        throw new Error(`[Radi.js] Error: Trying to write for reserved variable \`${key}\``);
      }
      this[key] = obj[key];
      if (type === 'head') this[key].when('update', () => this.setState());
    }
  }
@private
@param {object} obj
@param {string} type