fix megatron multi-lora converter

src/twinkle/model/megatron/megatron.py

@@ -1178,7 +1178,10 @@ def _save_megatron_format(self, output_dir: str, adapter_name: str, lora_convert
         cpu_state_dict = {}
         for k, v in state_dict.items():
             if lora_converter is not None:
-                k, v = lora_converter(k, v)
+                kv = lora_converter(k, v)
+                if kv is None:
+                    continue
+                k, v = kv
             if k is not None and v is not None:
                 cpu_state_dict[k] = v.cpu()
 

src/twinkle/model/multi_lora.py

@@ -494,7 +494,7 @@ def save_lora_converter(self, name, parameter, adapter_name):
             name = name.replace(f'.{_lora.adapter_name}.', '.')
             return name, _param
         else:
-            return None, None
+            return None
 
     def set_state_dict(self, tenant_adapter_name, state_dict):
         _lora = self.find_lora_by_tenant(tenant_adapter_name)