specials-service.ts

deleteStaleSpecials() {
  const specialsDeletionStatus = Promise.allSettled(
    this.specials
      .filter(({ stale }) => stale)
      .map((special) => this.deleteSpecial(special))
  );
  
  const rejectedCheckPredicate = ({ status }) => status === 'rejected';
  
  if (specialsDeletionStatus.some(rejectedCheckPredicate) {
    throw new Error(`Failed to delete some stale specials: ${
      specialsDeletionStatus
        .filter(rejectedCheckPredicate)
        .reduce((rejectionMessages, { reason }) => rejectionStatusMessages + reason, '')
    }`);
  }
  
  return specialsDeletionStatus;
}