session: fix coverity warnings

Change-Id: I022dc40476ea9c30957b12bf1bd0629c6eb41cda
Signed-off-by: Florin Coras <fcoras@cisco.com>
diff --git a/src/vnet/tls/tls.c b/src/vnet/tls/tls.c
index 040db02..d4c40f7 100644
--- a/src/vnet/tls/tls.c
+++ b/src/vnet/tls/tls.c
@@ -189,7 +189,8 @@
 {
   application_t *app;
   app = application_get_if_valid (app_session->app_index);
-  tls_add_app_q_evt (app, app_session);
+  if (PREDICT_TRUE (app != 0))
+    tls_add_app_q_evt (app, app_session);
 }
 
 int