issues: 1959175248

What happened?

da.xindexes or da.indexes raises an error when trying to generate the repr if there are no coords (indexes)

What did you expect to happen?

Displaying an empty Mappable?

Minimal Complete Verifiable Example

Python xr.DataArray([3, 5]).indexes xr.DataArray([3, 5]).xindexes

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, returning the result.
• [x] New issue — a search of GitHub Issues suggests this is not a duplicate.
• [x] Recent environment — the issue occurs with the latest version of xarray and its dependencies.

Relevant log output

```Python Out[9]: --------------------------------------------------------------------------- ValueError Traceback (most recent call last) File ~/.conda/envs/xarray_dev/lib/python3.10/site-packages/IPython/core/formatters.py:708, in PlainTextFormatter.call(self, obj) 701 stream = StringIO() 702 printer = pretty.RepresentationPrinter(stream, self.verbose, 703 self.max_width, self.newline, 704 max_seq_length=self.max_seq_length, 705 singleton_pprinters=self.singleton_printers, 706 type_pprinters=self.type_printers, 707 deferred_pprinters=self.deferred_printers) --> 708 printer.pretty(obj) 709 printer.flush() 710 return stream.getvalue()

File ~/.conda/envs/xarray_dev/lib/python3.10/site-packages/IPython/lib/pretty.py:410, in RepresentationPrinter.pretty(self, obj) 407 return meth(obj, self, cycle) 408 if cls is not object \ 409 and callable(cls.dict.get('repr')): --> 410 return _repr_pprint(obj, self, cycle) 412 return _default_pprint(obj, self, cycle) 413 finally:

File ~/.conda/envs/xarray_dev/lib/python3.10/site-packages/IPython/lib/pretty.py:778, in repr_pprint(obj, p, cycle) 776 """A pprint that just redirects to the normal repr function.""" 777 # Find newlines and replace them with p.break() --> 778 output = repr(obj) 779 lines = output.splitlines() 780 with p.group():

File ~/code/xarray/xarray/core/indexes.py:1659, in Indexes.repr(self) 1657 def repr(self): 1658 indexes = formatting._get_indexes_dict(self) -> 1659 return formatting.indexes_repr(indexes)

File ~/code/xarray/xarray/core/formatting.py:474, in indexes_repr(indexes, max_rows) 473 def indexes_repr(indexes, max_rows: int | None = None) -> str: --> 474 col_width = _calculate_col_width(chain.from_iterable(indexes)) 476 return _mapping_repr( 477 indexes, 478 "Indexes", (...) 482 max_rows=max_rows, 483 )

File ~/code/xarray/xarray/core/formatting.py:341, in _calculate_col_width(col_items) 340 def _calculate_col_width(col_items): --> 341 max_name_length = max(len(str(s)) for s in col_items) if col_items else 0 342 col_width = max(max_name_length, 7) + 6 343 return col_width

ValueError: max() arg is an empty sequence ```

Anything else we need to know?

No response

Environment

INSTALLED VERSIONS ------------------ commit: ccc8f9987b553809fb6a40c52fa1a8a8095c8c5f python: 3.10.12 | packaged by conda-forge | (main, Jun 23 2023, 22:40:32) [GCC 12.3.0] python-bits: 64 OS: Linux OS-release: 6.2.0-35-generic machine: x86_64 processor: x86_64 byteorder: little LC_ALL: None LANG: en_US.UTF-8 LOCALE: ('en_US', 'UTF-8') libhdf5: 1.14.2 libnetcdf: 4.9.2 xarray: 2023.9.1.dev8+gf6d69a1f pandas: 2.1.1 numpy: 1.24.4 scipy: 1.11.3 netCDF4: 1.6.4 pydap: installed h5netcdf: 1.2.0 h5py: 3.9.0 Nio: None zarr: 2.16.1 cftime: 1.6.2 nc_time_axis: 1.4.1 PseudoNetCDF: 3.2.2 iris: 3.7.0 bottleneck: 1.3.7 dask: 2023.9.2 distributed: None matplotlib: 3.8.0 cartopy: 0.22.0 seaborn: 0.12.2 numbagg: 0.2.2 fsspec: 2023.9.2 cupy: None pint: 0.20.1 sparse: 0.14.0 flox: 0.7.2 numpy_groupies: 0.10.1 setuptools: 68.2.2 pip: 23.2.1 conda: None pytest: 7.4.2 mypy: 1.5.1 IPython: 8.15.0 sphinx: None