I get the same error and found a bug that is causing this issue. The links for pages are not being generated correctly, see below for example.
<div id="wp-realtime-sitemap-pages"><h3>Pages</h3><ul>
<li class="page_item page-item-4 other"><a class="" href="https://domain.com/page/" title=""><a href="https://domain.com/page/</a></li>
