Some operation allowed to set invalid active scene render layer

Forbid this now and do tricks in the versioning code to repair
corrupted files.

Thanks to Pablo, Caminandes and Koro for discovering this bug!

1 files changed, 5 insertions, 0 deletions

diff --git a/source/blender/editors/space_node/node_edit.c b/source/blender/editors/space_node/node_edit.c
index fc0c82faba8..5bbe0c1c229 100644
--- a/source/blender/editors/space_node/node_edit.c
+++ b/source/blender/editors/space_node/node_edit.c
@@ -695,7 +695,12 @@ void ED_node_set_active(Main *bmain, bNodeTree *ntree, bNode *node)
 				for (scene = bmain->scene.first; scene; scene = scene->id.next) {
 					if (scene->nodetree && scene->use_nodes && ntreeHasTree(scene->nodetree, ntree)) {
 						if (node->id == NULL || node->id == (ID *)scene) {
+							int num_layers = BLI_countlist(&scene->r.layers);
 							scene->r.actlay = node->custom1;
+							/* Clamp the value, because it might have come from a different
+							 * scene which could have more render layers than new one.
+							 */
+							scene->r.actlay = min_ff(scene->r.actlay, num_layers - 1);
 						}
 					}
 				}