Merge branch 'v3' into user/tom/fix/v2-compat

Author: jhamman

src/zarr/core/array.py

@@ -315,7 +315,7 @@ async def _create_v2(
             chunks=chunks,
             order=order,
             dimension_separator=dimension_separator,
-            fill_value=fill_value,
+            fill_value=0 if fill_value is None else fill_value,
             compressor=compressor,
             filters=filters,
             attributes=attributes,