added exception in the Monolog context when appropriate (closes #613, closes #614)

composer.json

@@ -40,7 +40,8 @@
         "symfony/validator": ">=2.1,<2.3-dev",
         "twig/twig": ">=1.8.0,<2.0-dev",
         "doctrine/dbal": ">=2.2.0,<2.4.0-dev",
-        "swiftmailer/swiftmailer": "4.2.*"
+        "swiftmailer/swiftmailer": "4.2.*",
+        "monolog/monolog": "~1.4,>=1.4.1"
     },
     "suggest": {
         "symfony/browser-kit": ">=2.1,<2.3-dev",

src/Silex/Provider/MonologServiceProvider.php

@@ -73,9 +73,9 @@ class MonologServiceProvider implements ServiceProviderInterface
         $app->error(function (\Exception $e) use ($app) {
             $message = sprintf('%s: %s (uncaught exception) at %s line %s', get_class($e), $e->getMessage(), $e->getFile(), $e->getLine());
             if ($e instanceof HttpExceptionInterface && $e->getStatusCode() < 500) {
-                $app['monolog']->addError($message);
+                $app['monolog']->addError($message, array('exception' => $e));
             } else {
-                $app['monolog']->addCritical($message);
+                $app['monolog']->addCritical($message, array('exception' => $e));
             }
         }, 255);