Providing incorrect file to any *Model returns an empty object instead of a crash

[veenstrajelmer]

Describe the bug
Providing an incorrect file to any *Model class returns an empty object, while it would be clearer if an exception is raised.

To Reproduce
In the below example, the incorrect classes are called for reading this arbitrary file that should be read with hcdfm.XYNModel(). No warning/error is given, but instead an empty ObservationPointModel/ExtModel object is returned.

import hydrolib.core.dflowfm as hcdfm
file_xyn = 'obspoints_obs.xyn' #any file
data_xyn1 = hcdfm.ObservationPointModel(file_xyn)
data_xyn1 = hcdfm.ExtModel(file_xyn)

Version info (please complete the following information):

• OS: Windows and Spyder
• Version hydrolib-core from main branch

[priscavdsluis]

Might resolve #531 as well