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/3009#issuecomment-502731388,https://api.github.com/repos/pydata/xarray/issues/3009,502731388,MDEyOklzc3VlQ29tbWVudDUwMjczMTM4OA==,1217238,2019-06-17T15:27:25Z,2019-06-17T15:27:25Z,MEMBER,"> We're down to 1 failing test!
> 
> ```python
>         # Invalid cases
>         if not use_dask or LooseVersion(dask.__version__) > LooseVersion('0.17.4'):
>             with pytest.raises(TypeError):
> >               xr.dot(da_a, dims='a', invalid=None)
> E               Failed: DID NOT RAISE <class 'TypeError'>
> ```

I think this was an intentional change -- see https://github.com/dask/dask/pull/4914.","{""total_count"": 1, ""+1"": 1, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,454168102
https://github.com/pydata/xarray/issues/3009#issuecomment-502721965,https://api.github.com/repos/pydata/xarray/issues/3009,502721965,MDEyOklzc3VlQ29tbWVudDUwMjcyMTk2NQ==,1217238,2019-06-17T15:04:40Z,2019-06-17T15:04:40Z,MEMBER,"Xarray definitely had a bug with `ImplicitToExplicitIndexingAdapter`. See https://github.com/pydata/xarray/pull/3027 for the fix.

Unfortunately, this triggers new failures from inside dask's `blockwise_meta` helper:
```
>       return meta.astype(dtype)
E       AttributeError: 'ImplicitToExplicitIndexingAdapter' object has no attribute 'astype'
```

The bigger issue this surfaces is that I'm not sure whether `ImplicitToExplicitIndexingAdapter` (and xarray's other custom array types used for data loading) should be in `meta` or not. These array types overload indexing, but they don't implement the rest of NumPy's ndarray API. So it's a little strange to see them in `meta` (and of course methods like `astype` don't work on them).

On the other hand, they do need to be preserved rather than always cast to NumPy arrays. Otherwise repeated indexing like `x[i][j]` doesn't get optimized by dask, which turns out to be a really important optimization.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,454168102