Fix: pass ds_data as dictionary in read_schism_nc to circumvent xarray guard on xr.Dataset parameter

[aesgeorges]

Calling sx.read_schism_nc(grid, ds_data) raises:

TypeError: Passing a Dataset as `data_vars` to the Dataset constructor is not supported.
Use `ds.copy()` to create a copy of a Dataset.

Root

In read_schism_nc, ds_data (an xr.Dataset) is passed as positional argument to SxDataset which forwards it via *args through ux.UxDataset.__init__ down to xr.Dataset.__init__, where it lands in the data_vars parameter.

Newer versions of xarray (here 2026.4.0) added an explicit isinstance guard:

if isinstance(data_vars, Dataset):
    raise TypeError(...)

The error message is misleading however, as using ds_data.copy() instead in read_schism_nc creates another xr.Dataset, triggering the isinstance guard anyway.

Fix

Passing the data as a dictionary circumvents the guard, with dimension coordinates (such as time) being preserved.