From 205d7ae3f715095d1ec71ede7ff05f0c1b6c9fae Mon Sep 17 00:00:00 2001
From: Nicolas Grekas <nicolas.grekas@gmail.com>
Date: Thu, 18 Jan 2018 09:54:17 +0100
Subject: [PATCH] [Debug] Always decorate existing exception handlers to deal
 with fatal errors

---
 src/Symfony/Component/Debug/ErrorHandler.php | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/Symfony/Component/Debug/ErrorHandler.php b/src/Symfony/Component/Debug/ErrorHandler.php
index c0f07e256d..6a15f7b368 100644
--- a/src/Symfony/Component/Debug/ErrorHandler.php
+++ b/src/Symfony/Component/Debug/ErrorHandler.php
@@ -147,11 +147,14 @@ class ErrorHandler
             $handler = $prev[0];
             $replace = false;
         }
-        if ($replace || !$prev) {
-            $handler->setExceptionHandler(set_exception_handler(array($handler, 'handleException')));
-        } else {
+        if (!$replace && $prev) {
             restore_error_handler();
         }
+        if (is_array($prev = set_exception_handler(array($handler, 'handleException'))) && $prev[0] === $handler) {
+            restore_exception_handler();
+        } else {
+            $handler->setExceptionHandler($prev);
+        }
 
         $handler->throwAt($levels & $handler->thrownErrors, true);