DRW: Fix Crash in DRW_draw_depth_object when object batch cache is not init

This can happen if the viewport is not redrawn before calling an operator
(frequent in python scripting).

Related to T64805

source/blender/draw/intern/draw_manager.c

@@ -2590,6 +2590,8 @@ void DRW_draw_depth_object(ARegion *ar, GPUViewport *viewport, Object *object)
     world_clip_planes = rv3d->clip_local;
   }
 
+  drw_batch_cache_validate(object);
+
   switch (object->type) {
     case OB_MESH: {
       GPUBatch *batch;