switch with nested choice type with metadata does not parse/validate

[hugohills-regnosys]

switch with nested choice type with metadata does not parse/validate

  observable switch
      Asset   then Commodity exists,
      Basket  then basketConstituent extract [ Asset -> Commodity exists ] all = True,
      Index   then item ->> assetClass = Commodity, // this line causes issues
      default False 

where:

choice Observable: 
    Asset 
    Basket 
    Index 

choice Index: 
    CreditIndex 
    EquityIndex 
    FloatingRateIndex 
        [metadata location]
    ForeignExchangeRateIndex 
    OtherIndex

Note that if the problematic expression is replaced with item ->> assetClass exists then it works ok.

[hugohills-regnosys]

See CDM PR were it was introduced (and then reverted with workaround)
finos/common-domain-model@eb64a52

[SimonCockx]

Problem is not directly with the switch, but an error during indexing in the DerivedStateComputer.