[gnome-photos/wip/rishi/collection: 7/15] item-manager: Assert a few more invariants when going back from PREVIEW

[Debarshi Ray <debarshir src gnome org>]

commit 235270e249881a042215c743294982176d6476e7
Author: Debarshi Ray <debarshir gnome org>
Date:   Fri Jul 28 14:08:31 2017 +0200

    item-manager: Assert a few more invariants when going back from PREVIEW

 src/photos-item-manager.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)
---
diff --git a/src/photos-item-manager.c b/src/photos-item-manager.c
index c11c7c6..aa09582 100644
--- a/src/photos-item-manager.c
+++ b/src/photos-item-manager.c
@@ -1329,11 +1329,16 @@ photos_mode_controller_go_back (PhotosModeController *self)
     case PHOTOS_WINDOW_MODE_COLLECTIONS:
     case PHOTOS_WINDOW_MODE_FAVORITES:
     case PHOTOS_WINDOW_MODE_OVERVIEW:
-    case PHOTOS_WINDOW_MODE_PREVIEW:
     case PHOTOS_WINDOW_MODE_SEARCH:
       g_return_if_fail (old_mode != PHOTOS_WINDOW_MODE_PREVIEW);
       break;
 
+    case PHOTOS_WINDOW_MODE_PREVIEW:
+      g_return_if_fail (PHOTOS_IS_BASE_ITEM (self->active_object));
+      g_return_if_fail (self->active_object != (GObject *) self->active_collection);
+      g_return_if_fail (old_mode != PHOTOS_WINDOW_MODE_PREVIEW);
+      break;
+
     case PHOTOS_WINDOW_MODE_NONE:
     default:
       g_assert_not_reached ();