When a method uses a Gatherer.of(…) factory and provides a combiner function that always throws an exception, this implicitly signals
that the gatherer is designed for sequential processing. The java.util.stream.Gatherer API provides
Gatherer.ofSequential(…) factories which clearly indicates that the gatherer is intended for sequential streams. Using such a factory
improves code clarity, makes the intended processing model explicit, and avoids the need for a dummy or throwing combiner.
