[ErrorHandler] Fix exit code when an exception occurs and the exception handler has been unregistered

Author: nicolas-grekas

ErrorHandler.php

@@ -669,6 +669,10 @@ public static function handleFatalError(?array $error = null): void
             set_exception_handler($h);
         }
         if (!$handler) {
+            if (null === $error && $exitCode = self::$exitCode) {
+                register_shutdown_function('register_shutdown_function', function () use ($exitCode) { exit($exitCode); });
+            }
+
             return;
         }
         if ($handler !== $h) {
@@ -704,8 +708,7 @@ public static function handleFatalError(?array $error = null): void
             // Ignore this re-throw
         }
 
-        if ($exit && self::$exitCode) {
-            $exitCode = self::$exitCode;
+        if ($exit && $exitCode = self::$exitCode) {
             register_shutdown_function('register_shutdown_function', function () use ($exitCode) { exit($exitCode); });
         }
     }