Web push subscriptions are not removed in broadcasting

[hecsalazarf]

Subscription are not removed when they failed during broadcasting

// TODO Specify error for each user  because now the code does not
    // have the relationship error<->subscription per user
    if (await this.handleErrors(res, '#') === res.length) {
      // if all responses are errors, reject
      throw new Error('None message was delivered. All subscriptions were invalid'); // TODO return error array
    }