convertEachOrNull
inline fun <S : Any, T : Any> Iterable<S?>.convertEachOrNull(path: String, from: String, to: String, convert: (S) -> T?): List<T?>
Element ladder, List<T?> default (alignment preserved): null element → null pass-through, silent; broken element → null-in-place + MappingDegradation.AbsorbedConversionError whose cause is the TYPED exception from toMappingException. Length and index alignment are preserved. Only Exceptions are absorbed: CancellationException and Errors always propagate.