ErrorHandler can not throw errors because it will unsubscribe itself from
the error stream.
Zones captures errors and feed it into NgZone, which than has a Rx Observable
to feed it into ErrorHandler. If the ErroHandler throws, then Rx will teardown
the observable which in essence causes the ErrorHandler to be removed from the
error handling. This implies that the ErrorHandler can never throw errors.
Closes#14949Closes#15182Closes#14316