How to make an async operation to be SSR friendly (angular universal)
An Application bootstraps when it turns to be stable (ApplicationRef.isStable).
It happens on few cases. One of them is when there's no pending MacroTasks (NgZone.hasPendingMacrotasks).
Let's say you do a basic async request, for example using Fetch API. It's being scheduled as a MicroTask which means Angular treats it as something not important to wait for.
A solution could be to schedule a MacroTask. Take a look at an example implementation.