[Request] Allow error handlers to be overridden

[akuzemchak]

There are certain cases where I think developers may want to override previously defined error handlers. For example, let's say I have my main app, and also a REST API. I may want to define a 404 handler for the main app that displays a page:

App::missing(function($e)
{
    return Response::make(View::make('errors.404'), 404);
});

If the request is to one of my API's routes though, I might want my 404s to do this:

App::missing(function($e)
{
    return Response::json([
        'error' => 'Method not found',
    ], 404);
});

From what I can tell, there is no way to override the default 404 handler if the request is to an API route. This was possible in L3 with Event::override() and it would be awesome to get an equivalent in L4.

Thanks for the consideration!

[cmenke]

Unless I'm missing something, I think you could do something like this in your start/global.php:

App::error(function(Exception $exception, $code)
{
    Log::error($exception);

    if ($code == '404')
    {
        if (Request::ajax())
            return Response::json(array('error' => 'Method not found', 'code' => 404));

        return View::make('error.404');
    }
});

[akuzemchak]

I suppose that certainly would work for all intents and purposes... but say I were developing a package for distribution that needed to override an error handler (like for an admin bundle or something like that), it would be great to keep that code in the package's service provider, instead of needing to modify additional areas of the code.

[taylorotwell]

Done.