funk.php

<?php

$variables['blog_post']['teaser_image'] = [];
$variables['blog_post']['thumb_image'] = [];

/** @var NodeInterface $node */
if ($node->hasField('field_hero_image')) {
    /** @var \Drupal\Core\TypedData\ListInterface $fieldHeroImage */
    $fieldHeroImage = $node->get('field_hero_image');

    if (!$fieldHeroImage->isEmpty()) {
      try {
        /** @var \Drupal\Core\Field\Plugin\Field\FieldType\EntityReferenceItem||NULL $entityReferenceItem */
        $entityReferenceItem = $fieldHeroImage->first();

        if ($entityReferenceItem !== NULL) {
          /** @var \Drupal\Core\Entity\Plugin\DataType\EntityReference $entityReference */
          $entityReference = $entityReferenceItem->get('entity');

          /** @var \Drupal\Core\Entity\Plugin\DataType\EntityAdapter $entityAdapter */
          $entityAdapter = $entityReference->getTarget();

          /** @var \Drupal\media\MediaInterface $entity */
          $entity = $entityAdapter->getEntity();

          if ($entity->hasField('field_media_image')) {
            /** @var \Drupal\file\Plugin\Field\FieldType\FileFieldItemList $fileFieldItemList */
            $fileFieldItemList = $entity->get('field_media_image');

            /** @var \Drupal\image\Plugin\Field\FieldType\ImageItem $imageItem */
            $imageItem = $fileFieldItemList->first();

            if ($imageItem !== NULL) {
              $variables['blog_post']['teaser_image'] = $imageItem->view('teaser');
              $variables['blog_post']['thumb_image'] = $imageItem->view('thumbnail');
            }
          }
        }
      }
      catch (MissingDataException | \InvalidArgumentException $exception) {
      }
    }