public function _error($e) {
        $msg = sprintf('<h1>500 Internal Server Error</h1>'.
            '<h3>%s (%s)</h3>'.
            '<pre>%s</pre>',
            $e->getMessage(),
            $e->getCode(),
            $e->getTraceAsString()
        );

        try {
            $this->response()
                ->clear()
                ->status(500)
                ->write($msg)
                ->send();
        }
        catch (\Throwable $t) { // PHP 7.0+
            exit($msg);
        } catch(\Exception $e) { // PHP < 7
            exit($msg);
        }
    }