Fix T83869: Crash when creating Sequencer in new scene

Crash on null dereference in `SEQ_timeline_boundbox()`. This function was
generalized in rB9e4a4c2e996c to work on arbitrary `seqbase`.

Fixed by refactoring `SEQ_timeline_boundbox()` functions to return default
sane values if `seqbase` is `NULL`

Reviewed By: HooglyBoogly

Differential Revision: https://developer.blender.org/D9878

2 files changed, 2 insertions, 6 deletions

diff --git a/source/blender/editors/space_sequencer/sequencer_draw.c b/source/blender/editors/space_sequencer/sequencer_draw.c
index 5ad1e2399f5..d7d601a3c76 100644
--- a/source/blender/editors/space_sequencer/sequencer_draw.c
+++ b/source/blender/editors/space_sequencer/sequencer_draw.c
@@ -2305,7 +2305,7 @@ void draw_timeline_seq(const bContext *C, ARegion *region)
 
   UI_view2d_view_ortho(v2d);
   /* Get timeline bound-box, needed for the scroll-bars. */
-  SEQ_timeline_boundbox(scene, ed->seqbasep, &v2d->tot);
+  SEQ_timeline_boundbox(scene, SEQ_active_seqbase_get(ed), &v2d->tot);
   draw_seq_backdrop(v2d);
   UI_view2d_constant_grid_draw(v2d, FPS);
 
diff --git a/source/blender/editors/space_sequencer/sequencer_view.c b/source/blender/editors/space_sequencer/sequencer_view.c
index d2166705943..e12c43b7804 100644
--- a/source/blender/editors/space_sequencer/sequencer_view.c
+++ b/source/blender/editors/space_sequencer/sequencer_view.c
@@ -90,11 +90,7 @@ static int sequencer_view_all_exec(bContext *C, wmOperator *op)
   Scene *scene = CTX_data_scene(C);
   const Editing *ed = BKE_sequencer_editing_get(scene, false);
 
-  if (ed == NULL) {
-    return OPERATOR_FINISHED;
-  }
-
-  SEQ_timeline_boundbox(scene, ed->seqbasep, &box);
+  SEQ_timeline_boundbox(scene, SEQ_active_seqbase_get(ed), &box);
   UI_view2d_smooth_view(C, region, &box, smooth_viewtx);
   return OPERATOR_FINISHED;
 }