What happened?

Printing an empty slice of a DataArray with a RangeIndex coordinate raises an error.

What did you expect to happen?

No error.

Minimal Complete Verifiable Example

import numpy as np, xarray as xr, xarray.indexes

n = 30
step = 1
da = xr.DataArray(np.zeros(n), dims=["x"])
da = da.assign_coords(
    xr.Coordinates.from_xindex(
        xr.indexes.RangeIndex.linspace(0, (n - 1) * step, n, dim="x")))
sub = da.isel(x=slice(0))
print(sub)

MVCE confirmation

• Minimal example — the example is as focused as reasonably possible to demonstrate the underlying issue in xarray.
• Complete example — the example is self-contained, including all data and the text of any traceback.
• Verifiable example — the example copy & pastes into an IPython prompt or Binder notebook, returning the result.
• New issue — a search of GitHub Issues suggests this is not a duplicate.
• Recent environment — the issue occurs with the latest version of xarray and its dependencies.

Relevant log output

<elided traceback...>

File ~/.local/lib/python3.13/site-packages/xarray/indexes/range_index.py:299, in RangeIndex.step(self)
    296 @property
    297 def step(self) -> float:
    298     """Returns the spacing between values."""
--> 299     return self.transform.step

File ~/.local/lib/python3.13/site-packages/xarray/indexes/range_index.py:57, in RangeCoordinateTransform.step(self)
     55 @property
     56 def step(self) -> float:
---> 57     return (self.stop - self.start) / self.size

ZeroDivisionError: float division by zero

Anything else we need to know?

At least, the print should not error. Ideally, accessing the .step attribute of the coordinate would keep working and return the same step value as prior to slicing (and ::2-slicing an empty slice would double the step, similarly to what builtins.range does: range(0, 0, 3)[::2] == range(0, 0, 6)).
From a quick look, I'd guess that a proper fix would involve changing the internal representation of RangeCoordinateTransform from having start, stop, and size (well, dim_size) as attributes and step as a derived property to having start, size, and step as attributes and stop as a derived property.

Environment