/// <summary> /// Concatenate with the error signal. /// </summary> /// <param name="source">The source to append an error to</param> /// <param name="error">Th error to append</param> /// <typeparam name="TSource">The element type of the sequence</typeparam> /// <returns>The new IAsyncEnumerable instance.</returns> internal static IAsyncEnumerable <TSource> WithError <TSource>(this IAsyncEnumerable <TSource> source, Exception error) { return(source.ConcatWith(AsyncEnumerable.Error <TSource>(error))); }