rather then you die you `Mage::log('testing');`

Follow the below code

    <?php
    class Npm_Commission_Model_Observer extends Varien_Event_Observer
    {
        public function saveorder($observer)
        {
            Mage::log('sales_order_place_after');
            $params = Mage::app()->getFrontController()->getRequest()->getParams();
            Mage::log(print_r($params,true));
        }

Make you have enable log in Magento.

To check your data `var/log`.