我正在尝试在PHP中处理异常但堆栈错误仍然显示而不是由catch处理

I'm calling a method that I know could cause an error and I'm trying to handle the error by wrapping the code in a try/catch statement...

class TestController extends Zend_Controller_Action
{

    public function init()
    {
        // Anything here happens BEFORE the View has rendered
    }

    public function indexAction()
    {
        // Anything `echo`ed here is added to the end of the View
        $model = new Application_Model_Testing('Mark', 31);
        $this->view->sentence = $model->test();
        $this->loadDataWhichCouldCauseError();
        $this->loadView($model); // this method 'forwards' the Action onto another Controller
    }

    private function loadDataWhichCouldCauseError()
    {
        try {
            $test = new Application_Model_NonExistent();
        } catch (Exception $e) {
            echo 'Handle the error';
        }
    }

    private function loadView($model)
    {
        // Let's pretend we have loads of Models that require different Views
        switch (get_class($model)) {
            case 'Application_Model_Testing':
                // Controller's have a `_forward` method to pass the Action onto another Controller
                // The following line forwards to an `indexAction` within the `BlahController`
                // It also passes some data onto the `BlahController`
                $this->_forward('index', 'blah', null, array('data' => 'some data'));
                break;
        }
    }

}

...but the problem I have is that the error isn't being handled. When viewing the application I get the following error...

( ! ) Fatal error: Class 'Application_Model_NonExistent' not found in /Library/WebServer/Documents/ZendTest/application/controllers/TestController.php on line 23

Can any one explain why this is happening and how I can get it to work?

Thanks