DefaultConversionService throws confusing NoSuchElementException when converting invalid Enums

[lupiter]

Setting up Locations to convert a parameter to an Enum, as follows:

enum class State{
    ACTIVE,
    UNKNOWN
}

object Paths {
    @Location("/") class getBase(val `state`: List<State>? = null)
}

If request contains a value not in the Enum e.g. /?state=NO, or is empty /?state= then DefaultConversionService throws a NoSuchElementException because the call type.enumConstants.first fails to find a value.

Since the state is nullable it would be good if it could return null in the empty case. In the case of a wrong value it would be helpful if the generic NoSuchElementException could be wrapped in a DataConversionException which could be caught and return 400. A NoSuchElementException could have a variety of causes and would be a very generic catch.

[cy6erGn0m]

Not sure why empty values should be silently ignored? we only do like that only for missing values while empty values are handled as is