Drupal 8 check paragraph bundles and print out view modes in node.hml.twig

custom.theme.php

<?php
use Drupal\paragraphs\Entity\Paragraph;
/**
 * Implements template_preprocess_node
 *
 * Add variables for paragraphs available to node templates
 */
function CUSTOM_preprocess_node(&$variables) {

  // Convenience Variables
  $node = $variables['node'];

  // Empty Paragraph Variables for node.html.twig
  $section_image = [];
  $section_video = [];

  // Get $paragraph->bundle() types and assign variables if they exist
  if (!empty($node->field_sections->getValue())) {
    foreach ($node->field_sections->getValue() as $key => $value) {
      $paragraph = FALSE;
      if (!empty($value['entity'])) {
        // Use that, we're probably previewing.
        $paragraph = $value['entity'];
      }
      elseif (!empty($value['target_id'])) {
        $paragraph = Paragraph::load($value['target_id']);
      }
      if (!empty($paragraph) && $paragraph instanceof Paragraph) {
        $view_builder = $entity_type_manager->getViewBuilder('paragraph');
        $array = $view_builder->view($paragraph);
        $array['#cache']['tags'][] = 'node:' . $node->id();
        // Populate variable arrays
        if ($paragraph->bundle() == 'section_image') {
          $section_image[] = $array;
          // optionally change the view_mode
          foreach ($section_image as $key => $value) {
            $section_image[$key]['#view_mode'] = 'teaser';
          }
        }
        if ($paragraph->bundle() == 'section_video') {
          $section_video[] = $array;
          // optionally change the view_mode
          foreach ($section_video as $key => $value) {
            $section_video[$key]['#view_mode'] = 'teaser';
          }
        }
      }
    }
  }

  // Populated Variables
  $variables['section_image'] = $section_image;
  $variables['section_video'] = $section_video;

node.html.twig

  {% if section_video %}

    <p>this has a video!</p>
    {% for video in section_video %}
      {% if loop.first %}
        {{ video }}
      {% endif %}
    {% endfor %}

  {% elseif section_video is empty and section_image %}
    <p>this has no video but it has an image!</p>
    {% for image in section_image %}
      {% if loop.first %}
        {{ image }}
      {% endif %}
    {% endfor %}

  {% else %}

    <p>No media!</p>

  {% endif %}