How to detect an error when saving

I am saving multiple records. The code save multiple records but I dont understand how I can detect an error with saving in cakephp3.
The check I have in place will always return true I believe.

 if (!empty($data)){
       $lessons = $this->Lessons->newEntities($data, ['validate' => false]);
       //saves all in 1 transaction instead of 1 by 1
       $this->Lessons->connection()->transactional(function () use ( $lessons) {
       foreach ($lessons as $item) {
           $result=$this->Lessons->save($item, ['atomic' => false]);
          if ( $result ){   //this is the check for error when saving
             $this->Flash->success(__('A lesson has been saved on .'. $item->lesson_date));
              $this->Flash->error(__('There has been an error saving a lesson. Please, try again.'));
  }//if not empty

I think $this->Lessons->save() returns false when there’s error. If it is false, use $item->errors() to see the errors.

When there’s no error, $this->Lessons->save returns the saved entity. In this case, $result === $item.