Drupal 8 Create Block If Not Exists Function DB Update Script

<?php

/**
 * @file
 * DB post-updates for blocks.
 */

use Drupal\block_content\Entity\BlockContent;

/**
 * Create empty custom block content for new blocks that require them.
 */
function theme_blocks_post_update_2019_10_22(&$sandbox) {
  createBlockIfNotExists([
    'type' => 'block_type',
    'uuid' => '11ee98a0-2cd1-4285-a787-9c57117cfa66',
    'info' => 'block description...',
  ]);
}

function createBlockIfNotExists($block) {
  if (!blockExists($block['uuid'])) {
    BlockContent::create($block)->save();
  }
}

function blockExists($blockUuid) {
  return \Drupal::entityTypeManager()->getStorage('block_content')->loadByProperties(['uuid' => $blockUuid]);
}