code: public static <T> Mono<T> error(Supplier<Throwable> errorSupplier) {
  		return onAssembly(new MonoErrorSupplied<>(errorSupplier));
  	}
docs: Create a {@link Mono} that terminates with an error immediately after being
  subscribed to. The {@link Throwable} is generated by a {@link Supplier}, invoked
  each time there is a subscription and allowing for lazy instantiation.
  <p>
  <img class="marble" src="doc-files/marbles/errorWithSupplier.svg" alt="">
  <p>
  @param errorSupplier the error signal {@link Supplier} to invoke for each {@link Subscriber}
  @param <T> the reified {@link Subscriber} type
  
  @return a failing {@link Mono}