Fix (unreported) crash when deleting collection in freshly duplicated scene.

From startup .blend, add a 'full copy' new scene, and delete its
Collection 1.001 collection. That would make blender crash, once again
due to NULL collection pointer in some ChildrenCollection struct...

1 files changed, 6 insertions, 2 deletions

diff --git a/source/blender/blenkernel/intern/library_remap.c b/source/blender/blenkernel/intern/library_remap.c
index 8a011b55cf3..404028f336e 100644
--- a/source/blender/blenkernel/intern/library_remap.c
+++ b/source/blender/blenkernel/intern/library_remap.c
@@ -323,10 +323,14 @@ static void libblock_remap_data_postprocess_object_update(Main *bmain, Object *o
 /* Can be called with both old_collection and new_collection being NULL,
  * this means we have to check whole Main database then. */
 static void libblock_remap_data_postprocess_collection_update(
-        Main *bmain, Collection *old_collection, Collection *new_collection)
+        Main *bmain, Collection *UNUSED(old_collection), Collection *new_collection)
 {
 	if (new_collection == NULL) {
-		BKE_collections_child_remove_nulls(bmain, old_collection);
+		/* XXX Complex cases can lead to NULL pointers in other collections than old_collection,
+		 * and BKE_main_collection_sync_remap() does not tolerate any of those, so for now always check whole
+		 * existing collections for NULL pointers.
+		 * I'd consider optimizing that whole collection remapping process a TODO for later. */
+		BKE_collections_child_remove_nulls(bmain, NULL /*old_collection*/);
 	}
 
 	BKE_main_collection_sync_remap(bmain);