[WordPress] List all posts by taxonomy and paginate the list

<?php
/*
 * Based on https://wordpress.stackexchange.com/a/228071/11761
 *
 */

$post_type = 'item';
$taxonomy  = 'item_tags';

// count the number of terms for correct pagination
$term_count = get_terms( array (
	'taxonomy' => $taxonomy,
	'fields'   => 'count',
) );

// define the number of terms per page
$terms_per_page = 10;

// find out the number of pages to use in pagination
$max_num_pages = ceil( $term_count / $terms_per_page );

// get the page number from URL query
$current_page = get_query_var( 'paged', 1 );

// calculate offset
$offset = ( $terms_per_page * $current_page ) - $terms_per_page;

// get all taxonomy terms
$terms = get_terms( array (
	'taxonomy' => $taxonomy,
	'order'    => 'ASC',
	'orderby'  => 'name',
	'number'   => $terms_per_page,
	'offset'   => $offset,
) );

echo '<dl>';

// cycle through taxonomy terms
foreach ( $terms as $term ) {

	echo '<dt>' . $term->description . '</dt>';
	echo '<dd>'; 
	echo '<ul>';

	// cycle through posts having this term
	$items = get_posts( array (
		'post_type'   => $post_type,
		'tax_query'   => array(
			array(
				'taxonomy' => $taxonomy,
				'terms'    => $term->term_id,
			),
		),
		'numberposts' => -1, // different from WP_Query (see Code Ref)
	) );

	// essential, see comments inside foreach() loop
	global $post;

	foreach ( $items as $item ) {

		// assign $item to global $post 
		$post = $item;
		// and now set up 
		setup_postdata( $post );
	
		echo '<li><a href="' . get_the_permalink() . '">' . get_the_title() . '</a></li>';
		// wp_reset_postdata(); // see below
	}
	wp_reset_postdata(); // moved outside the foreach() loop

	// end posts cycle
	echo '</ul>';
	echo '</dd>';
}
// end term cycle
echo '</dl>';

// Pagination
// See the Code Reference for more arguments
echo paginate_links( array (
	'total'   => $max_num_pages,
	'current' => $current_page,
) );