Use annotation when you have call to undefined method get();

global $language;
$lang = $language->language;
$base_node = node_load(XXXXX);

$translations = translation_node_get_translations($base_node->tnid);
$translated_node = (isset($translations[$lang])?node_load($translations[$lang]->nid):$base_node);

function events_preprocess_node(&$variables) {
  // Get route name.
  $routeName = \Drupal::routeMatch()->getRouteName();
  // Get entity.
  $node = &$variables['node'];
  // Check if it's an event.
  if ($node->getType() === 'event' && $node->hasField('field_place')) {
    // Get the place.
    $place = $node->get('field_place')->entity;
    // Check if place is NULL.
    if ($place) {
      if ($node->get('field_teaser_media')->isEmpty()) {
        // Get teaser.
        $variables['place_teaser_media'] = $place
          ->get('field_teaser_media')
          ->view($routeName === 'entity.node.canonical' ? 'default' : 'small_teaser_square');
      }
      // Get organization name from place.
      $variables['place_organization'] = $place
        ->get('field_address')[0]
        ->get('organization')->getValue();
    }
  }
}

function mytheme_preprocess_node(&$variables) {
  switch ($variables['node']->getType()) {
    case "video":
      // ...
    break;
    case "something_else":
      // ...
    break;
  }
}			

// clear that cache
composer create-project drupal/recommended-project myproject -n
cd myproject
lando init --source cwd --recipe drupal8 --webroot web --name myproject
lando start


composer require drush/drush drupal/admin_toolbar
drush si --db-url=mysql://drupal8:drupal8@database/drupal8 --account-pass=content -y
drush en admin_toolbar admin_toolbar_tools
drush uli -l http://myproject.lndo.site

    /** @var \Drupal\bacademy_cpd\Entity\CpdPoints $cpd_record */
    foreach ($cpd_records as $cpd_record) {
      $completed_node = $cpd_record->get('node')->entity;
      /** @var \Drupal\node\Entity\Node $completed_node */
      $completed_nodeID = $completed_node->get('nid')->value;

$container = \Drupal::getContainer();

//If we don't want to cache anonymus user choices or content
//than we add next line of code in mymodule.routing.yml file
//for the specified page

no_cache: 'TRUE'

<?php

namespace Drupal\bacademy_core\Plugin\Block;

use Drupal\bacademy_core\Controller\SubscribeController;
use Drupal\Core\Block\BlockBase;
use Drupal\Core\Entity\EntityTypeManager;
use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
use Drupal\Core\Session\AccountProxyInterface;
use Drupal\Core\Url;
use Symfony\Component\DependencyInjection\ContainerInterface;
/**
 * Provides a 'Subscribe' block.
 *
 * @Block(
 *   id = "subscribe_block",
 *   admin_label= @Translation("Subscribe"),
 *   category= @Translation("Subscribe"),
 * )
 */
class SubscribeBlock extends BlockBase implements ContainerFactoryPluginInterface {

  /**
   * The current user.
   *
   * @var \Drupal\Core\Session\AccountProxyInterface
   */
  protected $currentUser;

  /**
   * Entity type manager.
   *
   * @var EntityTypeManager
   */
  protected $entityTypeManager;

  public function __construct(array $configuration, $plugin_id, $plugin_definition, AccountProxyInterface $current_user, EntityTypeManager $entityTypeManager) {
    parent::__construct($configuration, $plugin_id, $plugin_definition);
    $this->currentUser = $current_user;
    $this->entityTypeManager = $entityTypeManager;
  }

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition){
    return new static (
      $configuration,
      $plugin_id,
      $plugin_definition,
      $container->get('current_user'),
      $container->get('entity_type.manager')
    );
  }

  /**
   * {@inheritDoc}
   */
  public function build() {
    // Check if current user is subscribed.
    $user = $this->entityTypeManager
      ->getStorage('user')
      ->loadByProperties([
        'uid' => $this->currentUser->id(),
      ]);
    $user = reset($user);
    $subscribed = 0;
    if ($user->hasField('field_mailchimp_subscription')) {
      $subscribed = $user->get('field_mailchimp_subscription')[0]->get('subscribe')->getValue();
    }
    if ($subscribed == "1") {
      return [];
    } else {
      return [
        '#type' => 'inline_template',
        '#template' => "<div>
                        <p>Opt in and don't miss out on the latest from the Academy.</p>
                        <a href='{{ controller_link }}'>YES PLEASE</a>
                        <a href='#'>NO THANKS</a>
                      </div>",
        '#context' => [
          'controller_link' => Url::fromRoute('bacademy_core.subscription', ['id' => $this->currentUser->id()])->toString(),
        ],
      ];
    }
  }
}

<?php

namespace Drupal\bacademy_core\Controller;

use Drupal\Core\Controller\ControllerBase;
use Drupal\Core\Entity\EntityTypeManager;
use Drupal\Core\Url;
use Drupal\user\Entity\User;

class SubscribeController extends ControllerBase {

  public function __construct(EntityTypeManager $entityTypeManager) {
    $this->entityTypeManager = $entityTypeManager;
  }

  public function subscribe(int $id) {
    $user = $this->entityTypeManager->getStorage('user')->load($id);
    /** @var User $user */
    $subscribed = $user->get('field_mailchimp_subscription')[0]->get('subscribe')->getValue();
    if ($subscribed != "1") {
      $user->set('field_mailchimp_subscription', ['subscribe' => "1"] );
      $user->save();
      return Url::fromRoute('entity.user.canonical', ['user' => $user->id()])->toString();
    } else {
      return Url::fromRoute('entity.user.canonical', ['user' => $user->id()])->toString();
    }
  }
}

name: Subscribe block
type: module
description: Define a custom block for applying for subscription.
core_version_requirement: ^8 || ^9
package: Custom
dependencies:
  - block

$current_path = $this->request->getCurrentRequest()->headers->get('referer');
$path = explode('8000', $current_path);  
//8000 is just a part of a string, from where we are breaking the string.
$route_name = Url::fromUserInput($path[1])->getRouteName();
return $this->redirect($route_name, ['user' => $user->id()]);

$user->set('field_mailchimp_subscription', ['subscribe' => "1"]);

$media = \Drupal\file\Entity\File::load(2); //2 je target_id iz field_image (iz noda npr.).
dsm($media);