laravel 5 throws token error on facebook canvas - laravel-5

Question

I try to build a facebook canvas app using laravel 5. I use a custom middleware class to disable crsf for specific routes. can be found here. I ended up with another error.
Class 'App\Http\Middleware\TokenMismatchException' not found
This is my middlewareclass:
<?php namespace App\Http\Middleware;
use Closure;
class VerifyCsrfMiddleware extends \Illuminate\Foundation\Http\Middleware\VerifyCsrfToken
{
/**
* Handle an incoming request.
*
* #param \Illuminate\Http\Request $request
* #param \Closure $next
* #return mixed
*/
public function handle($request, Closure $next)
{
if ($this->isReading($request) || $this->excludedRoutes($request) || $this->tokensMatch($request))
{
return $this->addCookieToResponse($request, $next($request));
}
throw new TokenMismatchException;
}
/**
* Ignore CSRF on these routes.
*
* #param \Illuminate\Http\Request $request
* #return bool
*/
private function excludedRoutes($request)
{
$routes = [
'app/canvas'
// ... insert all your canvas endpoints here
];
foreach($routes as $route){
if ($request->is($route)) {
return true;
}
}
return false;
}
}