Locations in hvplot raises warning

[hoxbro]

ALL software version info

geoviews   : 1.9.5
holoviews  : 1.15.0a2
hvplot     : 0.8.0

Description of expected behavior and the observed behavior

When having features like coastline called by hvplot a warning is given with the latest dev release of holoviews. The warning is not present with version 1.14.

I have added the bug in Geoviews as this is where the warning is emitted from:

https://github.com/holoviz/geoviews/blob/1bd771233dfbd1208e86224f987c9003f121164a/geoviews/element/geo.py#L149-L150

Complete, minimal, self-contained example code that reproduces the issue

import xarray as xr
import hvplot.xarray

data = xr.tutorial.open_dataset("rasm").load()['Tair'].isel(time=0)
data.hvplot.quadmesh('xc', 'yc', coastline=True)

Screenshots or screencasts of the bug in action

With holoviews 1.15:

With holoviews 1.14:

[philippjfr]

Thanks @Hoxbro!

[hoxbro]

Fixed downstream by https://github.com/holoviz/hvplot/pull/850