title: array_diff gives Array to String conversion error in drupal
body: <p>I am experiencing a weird error from an array_diff statement. The statement is:</p>
  <p><code>$query = array_diff($params, array('f' =&gt; array()));</code></p>
  <p>and the <code>var_dump</code> of the <code>$params</code> is <code>array(1) { [&quot;f&quot;]=&gt; array(0) { } }</code></p>
  <p>This happens in a drupal module called <code>Islandora_solr_search</code> and I get the following error message twice like below</p>
  <blockquote>
  <p>Notice: Array to string conversion in IslandoraSolrResults-&gt;setBreadcrumbs() (line 427 of /var/www/drupal/sites/all/modules/islandora_solr_search/includes/results.inc).</p>
  <p>Notice: Array to string conversion in IslandoraSolrResults-&gt;setBreadcrumbs() (line 427 of /var/www/drupal/sites/all/modules/islandora_solr_search/includes/results.inc).</p>
  </blockquote>
  <p>Does anyone know why this happens?</p>