Fix T66567: Weight painting crashes with specific mesh

Seems the deform group index and deform vertices went out of sync somehow.

Added extra NULL pointer check, which seems to be safe and matches checks
in other places in the neighbourhood.

1 files changed, 5 insertions, 1 deletions

diff --git a/source/blender/blenkernel/intern/armature.c b/source/blender/blenkernel/intern/armature.c
index df22aa1dcfb..6d855df8af7 100644
--- a/source/blender/blenkernel/intern/armature.c
+++ b/source/blender/blenkernel/intern/armature.c
@@ -1370,7 +1370,11 @@ static void armature_vert_task(void *__restrict userdata,
   if (use_dverts || armature_def_nr != -1) {
     if (data->mesh) {
       BLI_assert(i < data->mesh->totvert);
-      dvert = data->mesh->dvert + i;
+      if (data->mesh->dvert != NULL) {
+        dvert = data->mesh->dvert + i;
+      } else {
+        dvert = NULL;
+      }
     }
     else if (data->dverts && i < data->target_totvert) {
       dvert = data->dverts + i;