interp1d does not accept scalar variable as input

[nvaytet]

Example:

x = sc.linspace(dim='x', start=0.1, stop=1.4, num=4, unit='rad')
da = sc.DataArray(sc.sin(x), coords={'x': x})
from scipp.scipy.interpolate import interp1d
f = interp1d(da, 'x')

xnew = sc.scalar(0.333, unit='rad')
f(xnew) 

raises

File ~/code/scipp/install/scipp/scipy/interpolate/__init__.py:188, in interp1d.<locals>.func(xnew, midpoints)
    182 if xnew.unit != da.coords[dim].unit:
    183     raise UnitError(
    184         f"Unit of interpolation points '{xnew.unit}' does not match unit "
    185         f"'{da.coords[dim].unit}' of points defining the interpolation "
    186         "function along dimension '{dim}'."
    187     )
--> 188 if xnew.dim != dim:
    189     raise DimensionError(
    190         f"Dimension of interpolation points '{xnew.dim}' does not match "
    191         f"interpolation dimension '{dim}'"
    192     )
    193 f = inter.interp1d(
    194     x=_as_interpolation_type(da.coords[dim].values),
    195     y=da.values,
   (...)
    198     **kwargs,
    199 )

DimensionError: Expected 1 dimensions, got 0

It would be nice if we could also send a single value and get a scalar back.