angular: UpgradeModule: Exception in $digest breaks change propagation

I’m submitting a…

[ ] Regression (a behavior that used to work and stopped working in a new release)
[x] Bug report  
[ ] Performance issue
[ ] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead see https://github.com/angular/angular/blob/master/CONTRIBUTING.md#question
[ ] Other... Please describe:

Current behavior

When $rootScope.$digest throws an exception ($digest already in progress), change propagation stops working for downgraded components.

That is because the exception breaks the subscription on onMicrotaskEmpty here:

https://github.com/angular/angular/blob/master/packages/upgrade/src/static/upgrade_module.ts#L244

setTimeout(() => {
  const $rootScope = $injector.get('$rootScope');
  const subscription = this.ngZone.onMicrotaskEmpty.subscribe(() => $rootScope.$digest());
  $rootScope.$on('$destroy', () => { subscription.unsubscribe(); });
}, 0);

Expected behavior

UpgradeModule should be more fault tolerant (try-catch?) or Use a different pattern. (Check if digest already running?)

Minimal reproduction of the problem with instructions

I get this “$digest already in progress” almost every time I open an angularjs material dialog or a sidenav.

What is the motivation / use case for changing the behavior?

Environment

Angular version: 6.0.X


Browser:
- [x] Chrome (desktop) version XX
- [ ] Chrome (Android) version XX
- [ ] Chrome (iOS) version XX
- [ ] Firefox version XX
- [ ] Safari (desktop) version XX
- [ ] Safari (iOS) version XX
- [ ] IE version XX
- [ ] Edge version XX