Issue #3263594: Incorrect handling of untranslatable (layout) paragraphs in...

    /** @var \Drupal\entity_reference_revisions\Plugin\Field\FieldType\EntityReferenceRevisionsItem $item */

    foreach ($items as $delta => $item) {

      if (!empty($item->entity) && $item->entity instanceof ParagraphInterface) {

        // Now we're sure it's a paragraph:

        $paragraph = $item->entity;

        if (!$this->isTranslating()) {

          // Set the langcode if we are not translating.

          $langcode_key = $item->entity->getEntityType()->getKey('langcode');

          if ($item->entity->get($langcode_key)->value != $this->langcode) {

          $langcode_key = $paragraph->getEntityType()->getKey('langcode');

          if ($paragraph->get($langcode_key)->value != $this->langcode) {

            // If a translation in the given language already exists,

            // switch to that. If there is none yet, update the language.

            if ($item->entity->hasTranslation($this->langcode)) {

              $item->entity = $item->entity->getTranslation($this->langcode);

            if ($paragraph->hasTranslation($this->langcode)) {

              $paragraph = $paragraph->getTranslation($this->langcode);

            }

            else {

              $item->entity->set($langcode_key, $this->langcode);

              $paragraph->set($langcode_key, $this->langcode);

            }

          }

        }

        else {

          // Add translation if missing for the target language.

          if (!$item->entity->hasTranslation($this->langcode)) {

          // Add translation if missing for the target language,

          // if the paragraph is translatable at all:

          if ($paragraph->isTranslatable() && !$paragraph->hasTranslation($this->langcode)) {

            // Get the selected translation of the paragraph entity.

            $entity_langcode = $item->entity->language()->getId();

            $entity_langcode = $paragraph->language()->getId();

            $source_langcode = $this->sourceLangcode ?? $entity_langcode;

            // Make sure the source language version is used if available.

            // Fetching the translation without this check could lead valid

            // scenario to have no paragraphs items in the source version of

            // to an exception.

            if ($item->entity->hasTranslation($source_langcode)) {

              $entity = $item->entity->getTranslation($source_langcode);

            if ($paragraph->hasTranslation($source_langcode)) {

              $paragraph = $paragraph->getTranslation($source_langcode);

            }

            // The paragraphs entity has no content translation source field

            // if no paragraph entity field is translatable,

            // even if the host is.

            if ($item->entity->hasField('content_translation_source')) {

            if ($paragraph->hasField('content_translation_source')) {

              // Initialise the translation with source language values.

              $item->entity->addTranslation($this->langcode, $entity->toArray());

              $translation = $item->entity->getTranslation($this->langcode);

              $paragraph->addTranslation($this->langcode, $paragraph->toArray());

              $translation = $paragraph->getTranslation($this->langcode);

              $manager = \Drupal::service('content_translation.manager');

              $manager->getTranslationMetadata($translation)

                ->setSource($item->entity->language()->getId());

                ->setSource($paragraph->language()->getId());

            }

          }

          // If any paragraphs type is translatable do not switch.

          if ($item->entity->hasField('content_translation_source')) {

          if ($paragraph->isTranslatable() && $paragraph->hasField('content_translation_source')) {

            // Switch the paragraph to the translation.

            $item->entity = $item->entity->getTranslation($this->langcode);

            $paragraph = $paragraph->getTranslation($this->langcode);

          }

        }

        $items[$delta]->entity = $item->entity;

        $items[$delta]->entity = $paragraph;

      }

    }

    $this->tempstore->set($this->layoutParagraphsLayout);