Hi, had the same issue.
the error message:
“call to a member function have_posts() on a non-object
wp-content/plugins/yuzo-related-post/yuzo_related_post.php on line 642”
I added the following:
is_object($the_query_yuzo)
on lines 642, 768, 973 ( in the “if” and the “while” statements)
It fixes the issue ,but i didn’t checked yet if it querys the correct posts
Hope it helps,
Thank You