Return empty array when configuration cannot be loaded

lib/Alchemy/Phrasea/Core/Provider/WorkerConfigurationServiceProvider.php

@@ -3,6 +3,7 @@
 namespace Alchemy\Phrasea\Core\Provider;
 
 use Alchemy\Phrasea\Core\Configuration\PropertyAccess;
+use Alchemy\Phrasea\Exception\RuntimeException;
 use Silex\Application;
 use Silex\ServiceProviderInterface;
 
@@ -37,6 +38,7 @@ class WorkerConfigurationServiceProvider implements ServiceProviderInterface
                 ]
             ];
 
+            try {
                 /** @var PropertyAccess $configuration */
                 $configuration = $app['conf'];
 
@@ -56,6 +58,10 @@ class WorkerConfigurationServiceProvider implements ServiceProviderInterface
                 $config = [ $queueConfiguration['name'] => $queueConfiguration ];
 
                 return $config;
+            }
+            catch (RuntimeException $exception) {
+                return [];
+            }
         });
     }
 
@@ -68,6 +74,6 @@ class WorkerConfigurationServiceProvider implements ServiceProviderInterface
      */
     public function boot(Application $app)
     {
-        // TODO: Implement boot() method.
+        // No-op
     }
 }