message: browser: add guard for window being undefined
  When the notifier is loaded via server-side rendering, we need to return
  early because `window` is not available.
diff: @@ -25,6 +25,10 @@ export class Notifier extends BaseNotifier {
  constructor(opt: IOptions) {
  super(opt);
  + if (typeof window === 'undefined') {
  + return;
  + }
  +
  this.addFilter(windowFilter);
  if (window.addEventListener) {
  