ensure title is set before adding

Closes #1051

Merge request studip/studip!614

lib/classes/Avatar.class.php

@@ -244,7 +244,7 @@ class Avatar {
             $opt['class'] = $this->getCssClass($size);
         }
 
-        if (isset($opt['title']) && $opt['title'] !== html_entity_decode($opt['title'])) {
+        if (!empty($opt['title']) && $opt['title'] !== html_entity_decode($opt['title'])) {
             // Decode already htmlready encoded titles (which were used until
             // all attributes were encoded inside this method)
             $opt['title'] = html_entity_decode($opt['title']);