html_url,issue_url,id,node_id,user,created_at,updated_at,author_association,body,reactions,performed_via_github_app,issue
https://github.com/pydata/xarray/issues/3717#issuecomment-577929592,https://api.github.com/repos/pydata/xarray/issues/3717,577929592,MDEyOklzc3VlQ29tbWVudDU3NzkyOTU5Mg==,161133,2020-01-23T23:42:27Z,2020-01-23T23:42:27Z,CONTRIBUTOR,"In the reduce call
https://github.com/pydata/xarray/blob/6d1434e9b9e9766d6fcafceb05e81734b29994ea/xarray/core/groupby.py#L877-L888

`dim` is assigned to a default of `self._group_dim` if it hasn't been specified. This should also check if `axis` hasn't been set.

The `check_reduce_dims()` call should then have a check for `dim is None` as well, so it's not run if `axis` is being used.

That should get you started","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,553930127