drupal 9 custom module to copy field data on save

copy fields.php

<?php


/**
 * Implements  hook_ENTITY_TYPE_presave().
 *
 * Prefill cost information for events if a previous event matches the same name and presenter.
 */
function libevents_node_presave(EntityInterface $node) {
  $title = '';
  $presenter = '';

  try {
    if ($node->isNew()) {
      if ($node->getType() == 'event') {

        // Get the current title and presenter
        $title = $node->getTitle();

        if ($node->get('field_search_tags')
          ->referencedEntities()[0]) {
          $presenter = $node->get('field_search_tags')
            ->referencedEntities()[0]->getTitle();
        }

        // Get the most recent node with the same title and presenter.
        $query = \Drupal::entityQuery('node')
          ->condition('title', $title, '=')
          ->condition('field_search_tags.entity.title', $presenter)
          ->sort('nid', 'DESC')
          ->range(0, 1);
        $nid = $query->execute();

        // If there is a match, preset the event financial fields
        if (isset($nid) && !empty($nid)) {
          $prev_node = Node::load(reset($nid));
          if($node->hasField('field_program_cost_code') && $prev_node->hasField('field_program_cost_code')) {
            $node->field_program_cost_code->target_id = $prev_node->get('field_program_cost_code')->target_id;
          }
          $node->set('field_professional_amount', $prev_node->get('field_professional_amount')->getValue());
          $node->set('field_professional_quantity', $prev_node->get('field_professional_quantity')->getValue());
          $node->set('field_preparation_quantity', $prev_node->get('field_preparation_quantity')->getValue());
          $node->set('field_preparation_amount', $prev_node->get('field_preparation_amount')->getValue());
          $node->set('field_travel_fee_amount', $prev_node->get('field_travel_fee_amount')->getValue());
          $node->set('field_free_amount', $prev_node->get('field_free_amount')->getValue());
        }
      }
    }
  } catch (Exception $e) {
    \Drupal::messenger()->addError($e->getMessage());
  }
}