bug #29584 [FrameworkBundle] fix describing routes with no controller…

…s (nicolas-grekas)

This PR was merged into the 3.4 branch.

Discussion
----------

[FrameworkBundle] fix describing routes with no controllers

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Spotted by @jpauli during a training.

Commits
-------

a1c612a [FrameworkBundle] fix describing routes with no controllers

src/Symfony/Bundle/FrameworkBundle/Console/Descriptor/TextDescriptor.php

@@ -56,7 +56,7 @@ protected function describeRouteCollection(RouteCollection $routes, array $optio
 
             if ($showControllers) {
                 $controller = $route->getDefault('_controller');
-                $row[] = $this->formatCallable($controller);
+                $row[] = $controller ? $this->formatCallable($controller) : '';
             }
 
             $tableRows[] = $row;