Missing Raise Value Error when using non-existing PET method

[markhegnauer]

When using a wrong PET method (non existing or typo), no ValueError is raised. leading to a very cryptic error message later on. Can be fixed on line 2036 in wflow.py

ValueError(f"Unknown pet method {pet_method}, select from {methods}")

should be

raise ValueError(f"Unknown pet method {pet_method}, select from {methods}")