`plot.scatter(hue_style="invalid")` does not raise an exception

[mgunyho]

What happened?

If I do a scatterplot with hue_style=x, where x is not "continuous" or "discrete", the result is the same as passing hue_style="continuous".

Probably related to #7907.

What did you expect to happen?

An invalid value should raise an exception.

Minimal Complete Verifiable Example

import matplotlib.pyplot as plt
import numpy as np
import xarray as xr

x = xr.DataArray(
    np.random.default_rng().random((10, 3)),
    coords=[
        ("idx", np.linspace(0, 1, 10)),
        ("color", [1, 2, 3]),
    ]
)

x.plot.scatter(x="idx", hue="color", hue_style="invalid", ax=plt.figure().gca())
plt.show()

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.

Relevant log output

No response

Anything else we need to know?

No response

Environment

Details

INSTALLED VERSIONS

commit: None
python: 3.8.10 (default, May 26 2023, 14:05:08)
[GCC 9.4.0]
python-bits: 64
OS: Linux
OS-release: 5.14.0-1059-oem
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: None
LANG: en_US.UTF-8
LOCALE: ('en_US', 'UTF-8')
libhdf5: None
libnetcdf: None

xarray: 2023.1.0
pandas: 1.4.3
numpy: 1.23.0
scipy: None
netCDF4: None
pydap: None
h5netcdf: None
h5py: None
Nio: None
zarr: None
cftime: None
nc_time_axis: None
PseudoNetCDF: None
rasterio: None
cfgrib: None
iris: None
bottleneck: None
dask: None
distributed: None
matplotlib: 3.5.3
cartopy: None
seaborn: None
numbagg: None
fsspec: None
cupy: None
pint: None
sparse: None
flox: None
numpy_groupies: None
setuptools: 44.0.0
pip: 20.0.2
conda: None
pytest: None
mypy: None
IPython: 8.12.2
sphinx: None

I also tried this on main at 3459e6f, the behavior is the same.