misc: also log file in error in from_file

mdto/mdto.py

@@ -1042,6 +1042,6 @@ def elem_to_mdto(elem: ET.Element, mdto_class: classmethod, mdto_xml_parsers: di
         return parse_bestand(children)
     else:
         raise ValueError(
-            f"Unexpected first child <{object_type}> in <MDTO>: "
+            f"Unexpected first child <{object_type}> in {mdto_xml}: "
             "expected <informatieobject> or <bestand>."
         )