title: Lumen 5.3 Undefined variable: closure
body: <p>From composer I Created a project from laravel/lumen. I un-commented the route middleware </p>
  
  <pre><code>$app-&gt;routeMiddleware([
      'auth' =&gt; App\Http\Middleware\Authenticate::class,
  ]);` 
  </code></pre>
  
  <p>and my routes added the auth middleware. </p>
  
  <pre><code>$app-&gt;get('/', ['middleware'=&gt;'auth'], function () use ($app) {
      return $app-&gt;version();
  });
  </code></pre>
  
  <p>I get <code>ErrorException in RoutesRequests.php line 656: Undefined variable: closure</code></p>
  
  <p>I googled this and it seams to be a problem in 5.2 but I have 5.3 downloaded. Without the middleware I Get <code>Lumen (5.3.3) (Laravel Components 5.3.*)</code></p>