Move sanity check of inputs within argument-parse function to fail fast

[atteggiani]

In the code there are several lines in which sanity check of inputs take place.
For example in the bounding_box class:

replace_landsurface/src/replace_landsurface_with_ERA5land_IC.py

Lines 59 to 78 in 2dcc1d7

	if Path(maskfname).exists():
	d = iris.load(maskfname, var)
	d = d[0]
	d = xr.DataArray.from_iris(d)
	lons = d['longitude'].data
	lonmin = np.min(lons)
	lonmax = np.max(lons)
	if lonmax > 180.:
	lonmax = lonmax-360.
	lats = d['latitude'].data
	latmin = np.min(lats)
	latmax = np.max(lats)
	d.close()
	else:
	print(f'ERROR: File {maskfname} not found', file=sys.stderr)
	raise

or

replace_landsurface/src/replace_landsurface_with_ERA5land_IC.py

Lines 81 to 85 in 2dcc1d7

	if Path(ncfname).exists():
	d = xr.open_dataset(ncfname)
	else:
	print(f'ERROR: File {ncfname} not found', file=sys.stderr)
	sys.exit(1)

Since the inputs for the class come from command line arguments (parsed through argparse in the hres_ic.py), it would be best to move all input argument's sanity check within a "parse_argument" function to:

• fail fast (at the beginning of the parent script)
• improve testing
• clear up code and group similar functionality all in one place