Reorganize structured fill parsing

Author: moradology

src/zarr/core/metadata/v2.py

@@ -296,20 +296,18 @@ def _parse_structured_fill_value(fill_value: Any, dtype: np.dtype[Any]) -> Any:
     """Handle structured dtype/fill value pairs"""
     try:
         if isinstance(fill_value, list):
-            fill_value = tuple(fill_value)
+            return tuple(fill_value)
         if isinstance(fill_value, tuple):
-            fill_value = np.array([fill_value], dtype=dtype)[0]
+            return np.array([fill_value], dtype=dtype)[0]
         elif isinstance(fill_value, bytes):
-            fill_value = np.frombuffer(fill_value, dtype=dtype)[0]
+            return np.frombuffer(fill_value, dtype=dtype)[0]
         elif isinstance(fill_value, str):
             decoded = base64.standard_b64decode(fill_value)
-            fill_value = np.frombuffer(decoded, dtype=dtype)[0]
+            return np.frombuffer(decoded, dtype=dtype)[0]
         else:
-            fill_value = np.array(fill_value, dtype=dtype)[()]
+            return np.array(fill_value, dtype=dtype)[()]
     except Exception as e:
-        msg = f"Fill_value {fill_value} is not valid for dtype {dtype}."
-        raise ValueError(msg) from e
-    return fill_value
+        raise ValueError(f"Fill_value {fill_value} is not valid for dtype {dtype}.") from e
 
 
 def parse_fill_value(fill_value: Any, dtype: np.dtype[Any]) -> Any: