Running getting_started notebook: ValueError: Model `164Dy` has default (None) variable `Z`

[hannahberg]

When running the getting_started notebook, I get a ValueError with the variable 'Z', this is solved when declaring norm_pars. Z = 66, but should this not be optional?

This is for ompy version '1.1.0.dev0+ce29c32'

ValueError                    Traceback (most recent call last)
<ipython-input-53-f68f11161851> in <module>
----> 1 gsfnorm.normalize()
      2 gsfnorm.plot()

~/.local/lib/python3.8/site-packages/ompy/normalizer_gsf.py in normalize(self, gsf, normalizer_nld, alpha, nld, nld_model, norm_pars, num)
    182 
    183         self.norm_pars = self.self_if_none(norm_pars)
--> 184         self.norm_pars.is_changed()  # check that they have been set
    185 
    186         # ensure to rerun

~/.local/lib/python3.8/site-packages/ompy/models.py in is_changed(self, include, exclude)
     55             val = getattr(self, key)
     56             if val is None:
---> 57                 raise ValueError(f"Model `{self.name}` has default (None) "
     58                                  f"variable `{key}`.")
     59             if isinstance(val, list):

ValueError: Model `164Dy` has default (None) variable `Z`.

[fzeiser]

Thank you for reporting this issue!