In Android RxJava, How to call same Single from two classes with and without observing

Question

In my Android app, I have a function that calls multiple APIs and creates a Single Response

fun callApis(): Single<Response>{
...
}

I want to reuse this function from two different classes. In one, I need to handle success and error. In the second class, I don't want to handle any response as there are multiple parallel API calls. How to achieve this?

What I currently do is From LoginViewModel.java

callApis().subscribe();

and from SettingsViewModel.java

callAppis().subscribe(
res -> handleSuccess();
throwable -> handleError();
);

But when any exception comes in callApis(), the LoginViewModel.java subscription will produce a OnErrorNotImplementedException. Is there any way to avoid this error?