code: public Searcher registerErrorListener(@NonNull AlgoliaErrorListener errorListener) {
          if (!errorListeners.contains(errorListener)) {
              errorListeners.add(errorListener);
          }
          return this;
      }
docs: Links the given listener to the Searcher, which will forward new search errors to it.
  
  @param errorListener an object implementing {@link AlgoliaErrorListener}.