public function checkFileValidity($filename)
    {
        try {
            $phar = new \Phar($filename);
            // free the variable to unlock the file
            unset($phar);
        } catch (\Exception $e) {
            if (!$e instanceof \UnexpectedValueException && !$e instanceof \PharException) {
                throw $e;
            }

            return 'Failed to create Phar instance. '.$e->getMessage();
        }

        return null;
    }
public function checkFileValidity($filename)
    {
        try {
            $phar = new \Phar($filename);
            // free the variable to unlock the file
            unset($phar);
        } catch (\Exception $e) {
            if (!$e instanceof \UnexpectedValueException && !$e instanceof \PharException) {
                throw $e;
            }

            return 'Failed to create Phar instance. '.$e->getMessage();
        }

        return null;
    }
{@inheritdoc}