using .setErrors doesn't trigger .errors$ to next()

[Burgov]

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
[ ] Other... Please describe:

Current behavior

Setting an error to a control using .setErrors() does not trigger a new value to be emitted from .errors$.

Expected behavior

calling .setErrors() should trigger .errors$ to emit

Minimal reproduction of the problem with instructions

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

We're calling .setErrors() based on a response from the API. Currently, this lib only checks for changes in errors directly after valueChanges, but since the API call is async, valueChanges is never triggered.

Environment

Angular version: 9.1.9


Browser:
- [ ] 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
 
For Tooling issues:
- Node version: XX  
- Platform:  

Others:

[NetanelBasal]

Do you want to create a PR?

[Burgov]

@NetanelBasal #47