Plot contour/contourf for crossect fails

[veenstrajelmer]

Plot contour for crosssect/mapslice raises "IndexError: index 1 is out of bounds for axis 1 with size 1" because edge_face_connectivity has shape (24336, 1)

MWE:

import dfm_tools as dfmt
import numpy as np
file_nc = dfmt.data.fm_grevelingen_map(return_filepath=True)
uds = dfmt.open_partitioned_dataset(file_nc)
line_array = np.array([[ 53181.96942503, 424270.83361629],
                       [ 55160.15232593, 416913.77136685]])
uds_crs = dfmt.polyline_mapslice(uds.isel(time=3), line_array)
uds_crs['mesh2d_sa1'].ugrid.plot(cmap='jet')
uds_crs['mesh2d_sa1'].ugrid.plot.contour()

This probably happens since we generate Ugrid2d based on crs_tstart and crs_tstop, with many overlapping values between crs_start[1:] and crs_stop[:-1]. The resulting node_x values are therefore not unique. However, the z on these x-unique points can be non-unique so we need this for flat water surfaces until xarray supports plotting bounds.

Wait on new xugrid cross section method/dataset from Deltares/xugrid#59