vars.get(date) returns invalid Date:

const camundaLib = require('camunda-external-task-client-js');
const vars = new camundaLib.Variables();
vars.set('date', new Date());
vars.get('date'); 

Root cause: Serialization Format is wrong, see https://github.com/camunda/camunda-external-task-client-js/issues/18 and https://github.com/camunda/camunda-external-task-client-js/blob/master/lib/__internal/utils.js#L168 for details