openlayers_ui_help() returns empty <p></p> if no output

The openlayers_ui module is causing blank advanced help to appear on EVERY page.

This is caused by openlayers_ui_help() returning a string even no path match occurred.

Error [line 98]:

return '<p>' . $output . '</p>';

---

Fix:

if (isset($output)) {
    return '<p>' . $output . '</p>'; 
}