Multicanonical option exception

[Charlotte-Knight]

With the default EventRates_Beam.yaml I am getting the following exception:

[FitterBase.cpp][info] Adding systematic object xsec_cov, with 301 params
[FitterBase.cpp][info] Adding BeamFD object, with 4 samples
terminate called after throwing an instance of 'YAML::InvalidNode'
  what():  invalid node; first invalid key: "Multicanonical"
Aborted (core dumped)

I found the existence of this option in the PDSP config

MaCh3_DUNE/Configs/FitterConfig_PDSP.yaml

Line 39 in 52d322d

Multicanonical:

so I am guessing that this is related to a new feature introduced by the PDSP updates.

I think wherever this option gets parsed in, it needs a catch to default to a default value if it is not in the yaml.

@wanyunSu @dlindebaum

[github-actions]

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