Raise error to test what cannot be stored in json config

[maxnoe]

No description provided.

[maxnoe]

With the changes made here, we are now down to the quantity, I can test if storing the string works now.

Concerning the enums, it might be better to not rely on the implicit IntEnum or StrEnum but add an explicit case that stores <Enum>.name into the json file.

We should also add a test that it's actually possible to round-trip with the config stored in the provenance, we don't have that as far as I can tell.

[kosack]

can test if storing the string works now.

What is allowed if these are specified on the command-line or in a YAML config? I guess it's just the string? There would in any case only be two options: a single string "option": "12 TeV" or separating it into value and unit, e.g. "option":{value="12",unit="TeV"}