code: public final <E extends Throwable> Mono<T> onErrorReturn(Class<E> type, T fallbackValue) {
  		return onErrorResume(type, throwable -> just(fallbackValue));
  	}
docs: Simply emit a captured fallback value when an error of the specified type is
  observed on this {@link Mono}.
  <p>
  <img class="marble" src="doc-files/marbles/onErrorReturnForMono.svg" alt="">
  
  @param type the error type to match
  @param fallbackValue the value to emit if an error occurs that matches the type
  @param <E> the error type
  
  @return a new falling back {@link Mono}