inertia-laravel: Custom `rootView` and shared data set in middleware not taken into account for errors (eg. 404)

The new HandleInertiaRequests middleware exposes a rootView property, allowing to set a custom root view.

It works fine for regular Inertia::render in controllers, but doesn’t seem to be taken into account when returning custom error views, as the doc suggests.

In my case, this happens for a 404 error. I imagine Laravel handles such errors differently: the request might not go through the middleware stack.

I just realized that it wouldn’t send the shared data to the error page either, nor would it version.

Here’s a stack trace:

[2020-10-29 15:26:42] local.ERROR: View [app] not found. {"exception":"[object] (InvalidArgumentException(code: 0): View [app] not found. at /<project>/vendor/laravel/framework/src/Illuminate/View/FileViewFinder.php:137)
[stacktrace]
#0 /<project>/vendor/laravel/framework/src/Illuminate/View/FileViewFinder.php(79): Illuminate\\View\\FileViewFinder->findInPaths('app', Array)
#1 /<project>/vendor/laravel/framework/src/Illuminate/View/Factory.php(138): Illuminate\\View\\FileViewFinder->find('app')
#2 /<project>/vendor/laravel/framework/src/Illuminate/Routing/ResponseFactory.php(85): Illuminate\\View\\Factory->make('app', Array)
#3 /<project>/vendor/laravel/framework/src/Illuminate/Support/Facades/Facade.php(261): Illuminate\\Routing\\ResponseFactory->view('app', Array)
#4 /<project>/vendor/inertiajs/inertia-laravel/src/Response.php(93): Illuminate\\Support\\Facades\\Facade::__callStatic('view', Array)
#5 /<project>/app/Exceptions/Handler.php(51): Inertia\\Response->toResponse(Object(Illuminate\\Http\\Request))
#6 /<project>/vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php(416): App\\Exceptions\\Handler->render(Object(Illuminate\\Http\\Request), Object(InvalidArgumentException))
#7 /<project>/vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php(114): Illuminate\\Foundation\\Http\\Kernel->renderException(Object(Illuminate\\Http\\Request), Object(InvalidArgumentException))
#8 /<project>/public/index.php(70): Illuminate\\Foundation\\Http\\Kernel->handle(Object(Illuminate\\Http\\Request))
#9 /Users/<user>/.composer/vendor/laravel/valet/server.php(191): require('/Users/<user>/d...')
#10 {main}
"}

---

// app/Http/Middleware/HandleInertiaRequests.php

class HandleInertiaRequests extends Middleware
{
    protected $rootView = 'layouts.dashboard';

    // ...
}

// app/Exceptions/Handler.php

class Handler extends ExceptionHandler
{
    // ...

    public function render($request, Throwable $e)
    {
        $response = parent::render($request, $e);

        if (in_array($response->status(), [403, 404, 500, 503])) {
            return Inertia::render('public/Error', ['status' => $response->status()])
                ->toResponse($request)
                ->setStatusCode($response->status());
        }

        return $response;
    }
}