Handle None values for HLO dump config keys.

Sets `dump_hlo_local_module_name` and `dump_hlo_module_name` to an empty string if they are provided as None.

PiperOrigin-RevId: 896185309

Author: Google-ML-Automation

src/maxtext/configs/pyconfig.py

@@ -83,9 +83,7 @@ def _resolve_or_infer_config(argv: list[str]) -> tuple[str, list[str]]:
     return resolve_config_path(argv[1]), argv[2:]
   module = _module_from_path(argv[0])
   if module not in _CONFIG_FILE_MAPPING:
-    raise ValueError(
-        f"No config file provided and no default config found for module '{module}'"
-    )
+    raise ValueError(f"No config file provided and no default config found for module '{module}'")
   config_path = os.path.join(MAXTEXT_CONFIGS_DIR, _CONFIG_FILE_MAPPING[module])
   logger.warning("No config file provided, using default config mapping: %s", config_path)
   return config_path, argv[1:]
@@ -203,6 +201,9 @@ def _prepare_for_pydantic(raw_keys: dict[str, Any]) -> dict[str, Any]:
     if key == "run_name" and new_value is None:
       new_value = ""
 
+    if key in ("dump_hlo_local_module_name", "dump_hlo_module_name") and new_value is None:
+      new_value = ""
+
     if key == "tokenizer_path" and new_value is None:
       try:
         new_value = HF_IDS[raw_keys["model_name"]]

tests/unit/pyconfig_test.py

@@ -122,10 +122,21 @@ def test_config_file_mapping(self):
 
   def test_module_from_path(self):
     import maxtext.trainers.pre_train.train as train_module
+
     module_file = train_module.__file__
     result = _module_from_path(module_file)
     self.assertEqual(result, "maxtext.trainers.pre_train.train")
 
+  def test_hlo_dump_module_names_none_coercion(self):
+    config = pyconfig.initialize(
+        [os.path.join(MAXTEXT_PKG_DIR, "train.py"), get_test_config_path()],
+        skip_jax_distributed_system=True,
+        dump_hlo_local_module_name=None,
+        dump_hlo_module_name=None,
+    )
+    self.assertEqual(config.dump_hlo_local_module_name, "")
+    self.assertEqual(config.dump_hlo_module_name, "")
+
   def test_unknown_module_raises(self):
     with self.assertRaises(ValueError):
       pyconfig.initialize_pydantic(["/custom_rl/module.py", "run_name=test"])