I noticed that xContribs sometimes outputs PHP and SQL errors on screen for various queries. For instance, this link shows SQL ones (maybe temporary?), instead if the searched used doesn't have any contribs (try this random link), there are actual PHP errors on screen which I'm also copying below:
Warning: array_sum() expects parameter 1 to be array, null given in <span style="font-weight:bold">/mnt/nfs/labstore-secondary-tools-project/erwin85/public_html/xcontribs.php</span> on line <span style="font-weight:bold">87</span> at Wed, 11 Jul 2018 11:43:30 +0000. Warning: Division by zero in <span style="font-weight:bold">/mnt/nfs/labstore-secondary-tools-project/erwin85/public_html/xcontribs.php</span> on line <span style="font-weight:bold">87</span> at Wed, 11 Jul 2018 11:43:30 +0000.