src/mg/Ding/Mvc/Http/HttpExceptionMapper.php
public function map(Action $action)
    {
        $exception = $action->getArguments();
        $exception = $exception['exception'];

        $this->_logger->debug('Exception mapper invoked with: ' . $action->getId());

        // Lookup a controller that can handle this url.
        foreach ($this->_map as $map) {
            $controllerException = $map[0];
            $controller = $map[1];
            if (!($exception instanceof $controllerException)) {
                continue;
            }
            return new DispatchInfo(
                $action, $controller,
                str_replace('\\', '_', $controllerException) . 'Exception'
            );
        }
        return false;
    }
public function map(Action $action)
    {
        $exception = $action->getArguments();
        $exception = $exception['exception'];

        $this->_logger->debug('Exception mapper invoked with: ' . $action->getId());

        // Lookup a controller that can handle this url.
        foreach ($this->_map as $map) {
            $controllerException = $map[0];
            $controller = $map[1];
            if (!($exception instanceof $controllerException)) {
                continue;
            }
            return new DispatchInfo(
                $action, $controller,
                str_replace('\\', '_', $controllerException) . 'Exception'
            );
        }
        return false;
    }
This will map an exception action to a controller. Will look for
an instance of the mapped exception to the thrown exception.

@param Action $action Original action (exception).

@return array [0] => Controller [1] => Method to call (With
'Exception' appended to the end of the method name).