id,node_id,number,title,user,state,locked,assignee,milestone,comments,created_at,updated_at,closed_at,author_association,active_lock_reason,draft,pull_request,body,reactions,performed_via_github_app,state_reason,repo,type
1680031454,I_kwDOAMm_X85kIz7e,7780,mypy does not understand output of binary operations,14371165,open,0,,,8,2023-04-23T13:38:55Z,2024-04-28T20:07:04Z,,MEMBER,,,,"### What happened?

When doing operations on numpy arrays and xarray variables mypy does not understand that the output is always a xarray variable regardless of the order. See example.


### What did you expect to happen?

mypy to pass for the example code.

### Minimal Complete Verifiable Example

```Python
import numpy as np
import xarray as xr


x = np.array([1, 2, 4])
v = xr.Variable([""x""], x)

# numpy first:
xv = x * v
xv.values  # error: ""ndarray[Any, dtype[bool_]]"" has no attribute ""values""  [attr-defined]
if isinstance(xv, xr.Variable):
    xv.values

# variable first:
vx = v * x
vx.values
if isinstance(vx, xr.Variable):
    vx.values
```


### MVCE confirmation

- [X] Minimal example — the example is as focused as reasonably possible to demonstrate the underlying issue in xarray.
- [X] Complete example — the example is self-contained, including all data and the text of any traceback.
- [X] Verifiable example — the example copy & pastes into an IPython prompt or [Binder notebook](https://mybinder.org/v2/gh/pydata/xarray/main?urlpath=lab/tree/doc/examples/blank_template.ipynb), returning the result.
- [X] New issue — a search of GitHub Issues suggests this is not a duplicate.

### Relevant log output

_No response_

### Anything else we need to know?

Seen in #7741

### Environment

<details>

xr.show_versions()

INSTALLED VERSIONS
------------------
commit: None
python: 3.9.16 (main, Mar  8 2023, 10:39:24) [MSC v.1916 64 bit (AMD64)]
python-bits: 64
OS: Windows
OS-release: 10
machine: AMD64
processor: Intel64 Family 6 Model 58 Stepping 9, GenuineIntel
byteorder: little
LC_ALL: None
LANG: en
libhdf5: 1.10.6
libnetcdf: None

xarray: 2023.4.2
pandas: 2.0.0
numpy: 1.23.5
scipy: 1.10.1
netCDF4: None
pydap: None
h5netcdf: None
h5py: 2.10.0
Nio: None
zarr: None
cftime: None
nc_time_axis: None
PseudoNetCDF: None
iris: None
bottleneck: None
dask: 2023.4.0
distributed: 2023.4.0
matplotlib: 3.5.3
cartopy: None
seaborn: 0.12.2
numbagg: None
fsspec: 2023.4.0
cupy: None
pint: None
sparse: None
flox: None
numpy_groupies: None
setuptools: 67.7.1
pip: 23.1.1
conda: 23.3.1
pytest: 7.3.1
mypy: 1.2.0
IPython: 8.12.0
sphinx: 6.1.3

</details>
","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/7780/reactions"", ""total_count"": 1, ""+1"": 1, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,,13221727,issue
1953053810,PR_kwDOAMm_X85dURGi,8344,Add mean to NamedArray._array_api,14371165,open,0,,,8,2023-10-19T21:05:06Z,2023-12-19T17:49:22Z,,MEMBER,,1,pydata/xarray/pulls/8344,"<!-- Feel free to remove check-list items aren't relevant to your change -->

- [ ] Closes #xxxx
- [ ] Tests added
- [ ] User visible changes (including notable bug fixes) are documented in `whats-new.rst`
- [ ] New functions/methods are listed in `api.rst`
","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/8344/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,,13221727,pull
970245117,MDExOlB1bGxSZXF1ZXN0NzEyMjIzNzc2,5704,Allow in-memory arrays with open_mfdataset,14371165,open,0,,,8,2021-08-13T09:50:26Z,2023-04-29T06:58:26Z,,MEMBER,,0,pydata/xarray/pulls/5704,"The docstring seems to imply that it's possible to get in-memory arrays:
https://github.com/pydata/xarray/blob/4bb9d9c6df77137f05e85c7cc6508fe7a93dc0e4/xarray/backends/api.py#L732

But it doesn't seem possible because of:
https://github.com/pydata/xarray/blob/4bb9d9c6df77137f05e85c7cc6508fe7a93dc0e4/xarray/backends/api.py#L899

This PR removes that `or` check, changes the default to `chunk={}`, and fixes the failing tests.

<!-- Feel free to remove check-list items aren't relevant to your change -->

- [x] Noticed in  #5689
- [ ] Closes #7792
- [x] Tests added
- [x] Passes `pre-commit run --all-files`
- [x] User visible changes (including notable bug fixes) are documented in `whats-new.rst`
","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/5704/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,,13221727,pull
931016490,MDExOlB1bGxSZXF1ZXN0Njc4NTc5MjIx,5542,Do not transpose 1d arrays during interpolation,14371165,open,0,,,8,2021-06-27T20:56:13Z,2022-10-12T20:12:11Z,,MEMBER,,0,pydata/xarray/pulls/5542,"Seems a waste of time to transpose 1d arrays.

<!-- Feel free to remove check-list items aren't relevant to your change -->

- [ ] Closes #xxxx
- [ ] Tests added
- [ ] Passes `pre-commit run --all-files`
- [ ] User visible changes (including notable bug fixes) are documented in `whats-new.rst`
- [ ] New functions/methods are listed in `api.rst`
","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/5542/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,,13221727,pull