In CodeBlob::create:

{
  ...
      blob = archived_blob->restore(code_cache_buffer,
                                    name,
                                    archived_reloc_data,
                                    archived_oop_maps);
#ifndef PRODUCT
      blob->use_remarks(archived_asm_remarks);
      archived_asm_remarks.clear();
      blob->use_strings(archived_dbg_strings);
      archived_dbg_strings.clear();
#endif // PRODUCT

      assert(blob != nullptr, "sanity check");
  ...
}

assert for blob != nullptr should be done immediately after the call to archived_blob->restore()