Fix T95815: missing null check when computing dupli dimensions

Some instances might be "empty" and therefore have no dimensions.
Those should be ignored here.

source/blender/blenkernel/intern/object.cc

@@ -4185,7 +4185,7 @@ bool BKE_object_minmax_dupli(Depsgraph *depsgraph,
 
   ListBase *lb = object_duplilist(depsgraph, scene, ob);
   LISTBASE_FOREACH (DupliObject *, dob, lb) {
-    if ((use_hidden == false) && (dob->no_draw != 0)) {
+    if (((use_hidden == false) && (dob->no_draw != 0)) || dob->ob_data == nullptr) {
       /* pass */
     }
     else {