[gnome-photos] application: Assert that it is a stateful GAction

[Debarshi Ray <debarshir src gnome org>]

commit 4bd6b4c7b561054ff8643417582041d55f69bb6e
Author: Debarshi Ray <debarshir gnome org>
Date:   Fri May 12 14:07:45 2017 +0200

    application: Assert that it is a stateful GAction

 src/photos-application.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)
---
diff --git a/src/photos-application.c b/src/photos-application.c
index 89b575d..95547e7 100644
--- a/src/photos-application.c
+++ b/src/photos-application.c
@@ -279,8 +279,7 @@ photos_application_action_toggle (GSimpleAction *simple, GVariant *parameter, gp
   GVariant *new_state;
 
   state = g_action_get_state (G_ACTION (simple));
-  if (state == NULL)
-    return;
+  g_return_if_fail (state != NULL);
 
   new_state = g_variant_new ("b", !g_variant_get_boolean (state));
   g_action_change_state (G_ACTION (simple), new_state);