simplify _load_sft_state_dict_metadata

Author: sayakpaul

src/diffusers/utils/state_dict_utils.py

@@ -355,11 +355,9 @@ def _load_sft_state_dict_metadata(model_file: str):
 
     from ..loaders.lora_base import LORA_ADAPTER_METADATA_KEY
 
-    metadata = None
     with safetensors.torch.safe_open(model_file, framework="pt", device="cpu") as f:
-        metadata = f.metadata()
-        if metadata is not None:
-            metadata_keys = list(metadata.keys())
-            if not (len(metadata_keys) == 1 and metadata_keys[0] == "format"):
-                metadata = json.loads(metadata[LORA_ADAPTER_METADATA_KEY])
-    return metadata
+        metadata = f.metadata() or {}
+
+    metadata.pop("format", None)
+    raw = metadata.get(LORA_ADAPTER_METADATA_KEY)
+    return json.loads(raw) if raw else None