Notice appear if page content is empty

I have created with a custom module a new page which while developing was empty:

<?php
function module_menu() {
  $items['new-path'] = array(
    'page callback' => 'module_new_path',
  );
  return $items;
}

function module_new_path() {
  return '';
}

In this situation appears the following notice message:
"Undefined index: content en theme_panels_everywhere_page() (line 21)"

The patch adds a comprobation that checks if content is set.