Glossary overview breaks html if $vocab->description is not set

Viewing the glossary overview my whole layout broke.
I found out that there is one closing div too much.
I tracked down the bug to function glossary_overview.

$output = '<div id="'. strtr(drupal_strtolower($vocab->name), $tbl) .'">';
  if ($vocab->description) {
    $output .= '<p class="glossary-description">'. $vocab->description .'</p>';
  }
  else {
    $output = null;
  }

My $vocab->description is not set. Therefore $output is set to null.
The function returns always return $output .'</div>'; but since $output was set to null the opening div vanishes, so there is a closing div too much.

I attach a patch removing the "else".
I don't know why this else is there, so maybe this is a bad idea ?
Please review.