working form for dtype classes

Author: d-v-b

src/zarr/core/array.py

@@ -699,7 +699,7 @@ def _create_metadata_v3(
 
         if fill_value is None:
             # v3 spec will not allow a null fill value
-            fill_value_parsed = dtype.type(zarr_data_type._default_value)
+            fill_value_parsed = zarr_data_type.default_value
         else:
             fill_value_parsed = fill_value