NotImplementedError: 'item' is not yet a valid method on dask arrays in cf_convert_between_lon_frames

[cehbrecht]

In clisops 0.16.2, subsetting fails when longitude coordinates are dask-backed.

The issue comes from this line in clisops/utils/dataset_utils.py

lon_min, lon_max = ds.coords[lon].min().item(), ds.coords[lon].max().item()

The .item() method only works on NumPy scalars. When applied to a dask-backed array, it raises:

NotImplementedError: 'item' is not yet a valid method on dask arrays

Suggested fix:

lon_min = float(ds.coords[lon].min().compute().values)
lon_max = float(ds.coords[lon].max().compute().values)

This forces evaluation before extracting the scalar and works with both NumPy and dask arrays.

Example:

In this notebook the error is reproduced using rooki via Rook WPS:

https://github.com/roocs/rooki/blob/master/notebooks/errors/cds-error-2025-09-08-cmip6-noresm2.ipynb