TYPING : Series.name -> Optional[Hashable]
xref https://github.com/pandas-dev/pandas/pull/29062#discussion_r337644656

cc @WillAyd @TomAugspurger 
No problem with changing but what caused this issue exactly? Something we need to account for with pickle compat? > No problem with changing but what caused this issue exactly? Something we need to account for with pickle compat?

no. with check_untyped_defs (i.e. checks body of _unpickle_series_compat)..

`None` is assigned to `name`: `index, name = own_state[0], None`

and then assigned to `self.name`: `self.name = name`

 Thanks!