www: Show full error message

Change-Id: I2e2dfe8852ef56d8c67a331e61e099de7b375013
diff --git a/src/EventListener/ExceptionListener.php b/src/EventListener/ExceptionListener.php
index ad5f108..83aefca 100644
--- a/src/EventListener/ExceptionListener.php
+++ b/src/EventListener/ExceptionListener.php
@@ -45,12 +45,14 @@
             default:
                 $html = $this->twig->render('errors/500.html.twig', [
                     'subject' => 'page',
-                    'message' => "Our server misbehaved. Bad Server, boo."
+                    'message' => $throwable->getMessage(),
+                    'trace' => $throwable->getTraceAsString()
                 ]);
                 $response = new Response();
                 $response->setContent($html);
 
                 $event->setResponse($response);
+                break;
         }
     }
 }
diff --git a/templates/errors/500.html.twig b/templates/errors/500.html.twig
index eb4139f..cc85fd4 100644
--- a/templates/errors/500.html.twig
+++ b/templates/errors/500.html.twig
@@ -13,6 +13,7 @@
     </span>
     <h1 style="color: var(--error-color)">Internal Server Error</h1>
     <h2>{{ message }}</h2>
+    <pre>{{ trace }}</pre>
 
     <div class="buttons">
       <a href="{{ path('leaf_home') }}">Return to home</a>