[syncd] Fix notification on shutdown request (sonic-net#635)

* [syncd] Fix notification on shutdown request

* Move check to the beginning of the function

Author: kcudnik

syncd/Syncd.cpp

@@ -3156,6 +3156,12 @@ void Syncd::sendShutdownRequest(
 {
     SWSS_LOG_ENTER();
 
+    if (m_notifications == nullptr)
+    {
+        SWSS_LOG_WARN("notifications pointer is NULL");
+        return;
+    }
+
     auto s = sai_serialize_object_id(switchVid);
 
     SWSS_LOG_NOTICE("sending switch_shutdown_request notification to OA for switch: %s", s.c_str());
@@ -3164,11 +3170,7 @@ void Syncd::sendShutdownRequest(
 
     // TODO use m_handler->onSwitchShutdownRequest(switchVid); (but this should be per switch)
 
-    if (m_notifications == nullptr)
-    {
-        SWSS_LOG_WARN("notifications pointer is NULL");
-        return;
-    }
+    s = sai_serialize_switch_shutdown_request(switchVid);
 
     m_notifications->send(SAI_SWITCH_NOTIFICATION_NAME_SWITCH_SHUTDOWN_REQUEST, s, entry);
 }