($lang).collections.$collectionHandle.($childCollectionHandle).ts

// Check if the collection has subcollections. We will only query for the metafield subcollection here.
  const {collection: metaSubcollection} = await context.storefront.query(
    METAFIELD_CHECK_QUERY,
    {
      variables: {
        handle: collectionHandle,
      },
    },
  );
  const subCollectionIds =
    metaSubcollection &&
    (metaSubcollection.metafields as any[]).length > 0 &&
    metaSubcollection.metafields[0]?.value
      ? JSON.parse(metaSubcollection.metafields[0].value)
      : null;

  let subCollectionHandles = [];

  if (
    subCollectionIds &&
    subCollectionIds != null &&
    (subCollectionIds as any[]).length > 0
  ) {
    const idsArray = Array.isArray(subCollectionIds)
      ? subCollectionIds
      : [subCollectionIds];

    // Get the handles of the subcollections. We will use this to check if the childCollectionHandle is a valid handle.
    const handleResponses = await Promise.all(
      idsArray.map((id) =>
        context.storefront.query(CHILDCOLLECTIONHANDLE_CHECK_QUERY, {
          variables: {
            id: id as string,
          },
        }),
      ),
    );

    subCollectionHandles = handleResponses
      .map((response) =>
        response.collection ? response.collection.handle : null,
      )
      .filter(Boolean);

    // Check if on childCollectionRoute
    if (
      childCollectionHandle &&
      !subCollectionHandles.includes(childCollectionHandle)
    ) {
      throw new Response('collection', {status: 404});
    }
  } else if (childCollectionHandle) {
    throw new Response('collection', {status: 404});
  }

  const {collection, collections} = await context.storefront.query<{
    collection: CollectionType;
    collections: CollectionConnection;
  }>(COLLECTION_QUERY, {
    variables: {
      ...paginationVariables,
      handle: childCollectionHandle ?? collectionHandle,
      filters,
      sortKey,
      reverse,
      country,
      language,
    },
  });