Syntax miskate of a subpage crashes twig template


today I had the case that a user made a Markdown syntax mistake in one of the news sub pages. This caused the complete news site to crash because the “childPage.summary(250)” statement tried to get the first 250 characters from the broken sub page.

{% for childPage in page.children.visible %}
    <h2><a href="{{ childPage.url }}">{{ childPage.title }}</a></h2>
    <p>{{ childPage.summary(250) }}</p>
    <p><a class="btn btn-secondary" href="{{ childPage.url }}" role="button">More &raquo;</a></p>
  <hr />
{% endfor %}

This resulted in following error message:

grav.CRITICAL: An exception has been thrown during the rendering of a template ("Malformed URL: http://").

The reason was the malformed url as stated in the error message.

My question is: Is there any way to prevent this? Something like ahh okay this sub page is broken, lets skip this one?

Best Regards