Sostituisci il seguente codice:
if ($this->actContentObject->language_id != 0) {
$confirm="onchange=\"confirmChangeLanguage('".$this->actContentObject->language."','".$this->actContentObject->language_id."')\"";
}
$langlist = JHTML::_('select.genericlist', $langOptions, 'language_id', 'class="inputbox" size="1" '.$confirm, 'value', 'text', $this->actContentObject->language_id );
con questo:
if ( isset($this->actContentObject) ) {
if ($this->actContentObject->language_id != 0) {
$confirm="onchange=\"confirmChangeLanguage('".$this->actContentObject->language."','".$this->actContentObject->language_id."')\"";
}
$langlist = JHTML::_('select.genericlist', $langOptions, 'language_id', 'class="inputbox" size="1" '.$confirm, 'value', 'text', $this->actContentObject->language_id );
} else {
$langlist = JHTML::_('select.genericlist', $langOptions, 'language_id', 'class="inputbox" size="1" '.$confirm, 'value', 'text');
}