TYPO3 Core

After using the hook ($GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['workspaces']['viewSingleRecord']) in the viewSingleRecord method in class tx_Workspaces_Service_Workspaces I received the following error:
"Cannot pass parameter 3 by reference in /srv/www/typo3_src-4.5.3/typo3/sysext/workspaces/Classes/Service/Workspaces.php on line 516"
As you can see the 3rd parameter in t3lib_div::callUserFunction is null:

public static function viewSingleRecord($table, $uid, $record=null) {
        $viewUrl = '';
        debug($viewUrl);
        if ($table == 'pages') {
                $viewUrl = t3lib_BEfunc::viewOnClick(t3lib_BEfunc::getLiveVersionIdOfRecord('pages', $uid));
        } elseif ($table  'pages_language_overlay' || $table  'tt_content') {
            $elementRecord = is_array($record) ? $record : t3lib_BEfunc::getLiveVersionOfRecord($table, $uid);
            $viewUrl = t3lib_BEfunc::viewOnClick($elementRecord['pid']);
        } else {
            if (isset($GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['workspaces']['viewSingleRecord'])) {
                $_params = array('table' => $table, 'uid' => $uid, 'record' => $record);
                $_funcRef = $GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['workspaces']['viewSingleRecord'];
                $viewUrl = t3lib_div::callUserFunction($_funcRef, $_params, null);
            }
        }
        return $viewUrl;
    }

After removing 3rd parameter null and simply passing only $_funcRef and $_params it worked fine.