code: function updateItem(id, updater) {
    return new Promise((resolve, reject) => {
      return instance.pkgs.then(db => {
        const obj = db.transaction(db.name, 'readwrite')
          .objectStore(db.name);
        const req = obj.get(id);
        req.onerror = event => reject(event);
        req.onsuccess = event => {
          const res = event.target.result;
          updater(res);
          const upd = obj.put(res);
          upd.onsuccess = () => resolve();
          upd.onerror = event => reject(event);
        };
      });
    });
  }
docs: Update package in the store
  @param {string} id - Package instance ID
  @param {function} updater - update function