How to enforce a specific aspect ratio for all Media images?

With the core media Image type, I want to restrict uploaded images by aspect ratio.

I want to block images that have the wrong aspect ratio from being uploaded. My question is the same as this Drupal 7 question, but for Drupal 8+.

This helpful blog post gave me an answer:

/**
 * Implements hook_form_alter().
 */
function MYMODULE_form_alter(&$form, FormStateInterface $form_state, $form_id) {
  switch ($form_id) {
    case 'media_image_add_form':
    case 'media_image_edit_form':
      $form['field_media_image']['widget'][0]['#upload_validators']['_validate_image_aspect_ratio'] = [];
      break;
  }
}

/**
 * Ensures that images have a square aspect ratio.
 *
 * @param \Drupal\file\FileInterface $file
 *   File object.
 *
 * @return array
 *   Errors array.
 */
function _validate_image_aspect_ratio(FileInterface $file) {
  $errors = [];
  $image = \Drupal::service('image.factory')->get($file->getFileUri());
  if ($image->isValid()) {
    // Add your condition validations here!
    $width = $image->getWidth();
    $height = $image->getHeight();
    $aspect_ratio = $width / $height;
    if ($aspect_ratio != 1 / 1) {
      $errors[] = t("The image should be a square!");
    }
  }
  return $errors;
}