Fix T66630 X-Ray + Subdivision surface Face select problem

source/blender/blenkernel/intern/modifier.c

@@ -785,6 +785,9 @@ bool modifiers_usesSubsurfFacedots(struct Scene *scene, Object *ob)
   VirtualModifierData virtualModifierData;
   ModifierData *md = modifiers_getVirtualModifierList(ob, &virtualModifierData);
   int cage_index = modifiers_getCageIndex(scene, ob, NULL, 1);
+  if (cage_index == -1) {
+    return false;
+  }
   /* Find first modifier enabled on cage. */
   for (int i = 0; md && i < cage_index; i++) {
     md = md->next;