http_static: validate session before sending

Type: fix

Signed-off-by: Florin Coras <fcoras@cisco.com>
Change-Id: I18b9d0d67f5fe4c1714427259df29026153d8dd1
diff --git a/src/plugins/http_static/static_server.c b/src/plugins/http_static/static_server.c
index b92af89..cd36be7 100644
--- a/src/plugins/http_static/static_server.c
+++ b/src/plugins/http_static/static_server.c
@@ -133,6 +133,8 @@
   hss_session_t *hs;
 
   hs = hss_session_get (args->sh.thread_index, args->sh.session_index);
+  if (!hs)
+    return;
 
   if (hs->data && hs->free_data)
     vec_free (hs->data);