[gnome-photos] collection-icon-watcher: We can't add a weak reference to NULL

[Debarshi Ray <debarshir src gnome org>]

commit adf2c615689c0ff072a04db081faef8ff3575b66
Author: Debarshi Ray <debarshir gnome org>
Date:   Thu May 7 20:11:01 2015 +0200

    collection-icon-watcher: We can't add a weak reference to NULL

 src/photos-collection-icon-watcher.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/src/photos-collection-icon-watcher.c b/src/photos-collection-icon-watcher.c
index cdd6e05..beb0cb3 100644
--- a/src/photos-collection-icon-watcher.c
+++ b/src/photos-collection-icon-watcher.c
@@ -396,7 +396,8 @@ photos_collection_icon_watcher_set_property (GObject *object,
     {
     case PROP_COLLECTION:
       priv->collection = PHOTOS_BASE_ITEM (g_value_get_object (value)); /* self is owned by collection */
-      g_object_add_weak_pointer (G_OBJECT (priv->collection), (gpointer *) &priv->collection);
+      if (priv->collection != NULL)
+        g_object_add_weak_pointer (G_OBJECT (priv->collection), (gpointer *) &priv->collection);
       break;
 
     default: