Fix crashes running operators in invalid contexts

Fix for running operators outside of expected contexts.

- UI_OT_view_drop (poll)
- UI_OT_view_item_rename (poll)
- OBJECT_OT_gpencil_modifier_move_to_index
- OBJECT_OT_modifier_move_to_index
- OBJECT_OT_geometry_nodes_input_attribute_toggle
- OBJECT_OT_geometry_node_tree_copy_assign
- OBJECT_OT_shaderfx_remove
- OBJECT_OT_shaderfx_copy
- POSE_OT_relax (& other pose slide operators).

1 files changed, 10 insertions, 6 deletions

diff --git a/source/blender/editors/util/ed_draw.c b/source/blender/editors/util/ed_draw.c
index 1b6a3efe19c..0fec8349796 100644
--- a/source/blender/editors/util/ed_draw.c
+++ b/source/blender/editors/util/ed_draw.c
@@ -370,11 +370,13 @@ tSlider *ED_slider_create(struct bContext *C)
   slider->factor = 0.5;
 
   /* Add draw callback. Always in header. */
-  LISTBASE_FOREACH (ARegion *, region, &slider->area->regionbase) {
-    if (region->regiontype == RGN_TYPE_HEADER) {
-      slider->region_header = region;
-      slider->draw_handle = ED_region_draw_cb_activate(
-          region->type, slider_draw, slider, REGION_DRAW_POST_PIXEL);
+  if (slider->area) {
+    LISTBASE_FOREACH (ARegion *, region, &slider->area->regionbase) {
+      if (region->regiontype == RGN_TYPE_HEADER) {
+        slider->region_header = region;
+        slider->draw_handle = ED_region_draw_cb_activate(
+            region->type, slider_draw, slider, REGION_DRAW_POST_PIXEL);
+      }
     }
   }
 
@@ -465,7 +467,9 @@ void ED_slider_status_string_get(const struct tSlider *slider,
 void ED_slider_destroy(struct bContext *C, tSlider *slider)
 {
   /* Remove draw callback. */
-  ED_region_draw_cb_exit(slider->region_header->type, slider->draw_handle);
+  if (slider->draw_handle) {
+    ED_region_draw_cb_exit(slider->region_header->type, slider->draw_handle);
+  }
   ED_area_status_text(slider->area, NULL);
   ED_workspace_status_text(C, NULL);
   MEM_freeN(slider);