On unmatchable routes, AsseticModule has no method of rendering a default or on_error style sheet.

[mrferos]

Regular 404s where a route is matched but there is no corresponding method to handle the route work just fine.

The case where a route can not be matched are not handled however, like:

http://site.com/this/route/will/not/match.jpg

I was able to handle this case by sort of re-implementing the renderAssets method in AsseticBundle/Listener.php but perhaps there should be some sort of configuration option to handle this case. My fix for the issue is below:

Application/Module.php

class Module
{
    public function onBootstrap(MvcEvent $e)
    {
        $e->getApplication()->getEventManager()->attach(MvcEvent::EVENT_DISPATCH_ERROR, array($this, 'handleDispatchError'), 32);
    }

    public function handleDispatchError(MvcEvent $e)
    {
        $sm = $e->getApplication()->getServiceManager();
        if ($e->getName() != MvcEvent::EVENT_DISPATCH_ERROR)
            return;

        $config = $sm->get('AsseticConfiguration');
        if ($e->getName() === MvcEvent::EVENT_DISPATCH_ERROR) {
            $error = $e->getError();
            if ($error && !in_array($error, $config->getAcceptableErrors())) {
                // break if not an acceptable error
                return;
            }
        }

        $response = $e->getResponse();
        if (!$response) {
            $response = new Response();
            $e->setResponse($response);
        }

        $routeMatch = $e->getRouteMatch();
        if ($routeMatch)
            return;

        /** @var $asseticService \AsseticBundle\Service */
        $asseticService = $sm->get('AsseticService');

        $asseticService->setRouteName('error_404');
        $asseticService->setControllerName('Application\Controller\Index');
        $asseticService->setActionName('error_' . uniqid());

        // Create all objects
        $asseticService->build();

        // Init assets for modules
        $asseticService->setupRenderer($sm->get('ViewRenderer'));

    }
}

Snippet from module.config.php

return array(
    'assetic_configuration' => array(
        'debug' => true,
        'buildOnRequest' => true,
        'webPath' => __DIR__ . '/../../../public/assets',
        'basePath' => 'assets',
        'routes' => array(
            'error_404' => array(
                '@base_css',
                '@head_home_js'
            ),
      )
);

[widmogrod]

Did you notice any issues after "reordering"?