AWS Neptune and gremlin-javascript versions

ResponseError: Server error: {"code":"InternalFailureException","requestId":"aa89ee40-74d5-46c1-9ad5-0bc3f2fde5c1","detailedMessage":"null: .option(LinkedHashMap, LinkedHashMap)","message":"null: .option(LinkedHashMap, LinkedHashMap)"} (599)

const {
    t: { id, label }
} = gremlin.process;

const idMap = new Map([[id, entity.id]]);
const createMap = new Map([
            [label, 'my_vertex'],
            ['prop1', entity.prop1 || '']
        ]);
const updateMap = new Map([
            ['prop1', entity.prop1 || '']
        ]);
return g
       .mergeV(idMap)
       .option(onCreate, createMap)
       .option(onMatch, __.sideEffect(__.property(cardinality.single, updateMap)).constant(new Map()));