UnhandledPromiseRejectionWarning: Unhandled promise rejection

[splincode]

$ npm run serve

> [email protected] serve C:\Develop\angular-kotlin-starter
> webpack-dev-server --open

Project is running at http://localhost:8080/
webpack output is served from /
Content not from webpack is served from ./www
"kotlinc-js" �� ���� ����७��� ��� ���譥�
��������, �ᯮ��塞�� �ணࠬ��� ��� ������ 䠩���.

(node:6520) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): TypeError: Cannot read property 'forEach' of undefined
(node:6520) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
webpack: wait until bundle finished: /


$ node -v
v8.9.1

$ npm -v
6.1.0