MinioClient.ListObjectsAsync() throws an error when the bucket is empty

As the title says, simple code:

            try
            {
                await this.client.ListObjectsAsync(bucketName);
                return true;
            }
            catch
            {
                return false;
            }

always returns false, when the requested bucket does not contain any objects (e.g. new bucket).

The caught exception is:

System.InvalidOperationException: Sequence contains no elements.
   at System.Reactive.Subjects.AsyncSubject`1.GetResult() in D:\a\1\s\Rx.NET\Source\src\System.Reactive\Subjects\AsyncSubject.cs:line 361

[BigUstad]

Having await on a function that is not marked async and returns IObservable may be causing an unintended error. Can you please remove the await keyword for ListObjectsAsync & try.

[BigUstad]

Fix 527 merged to master branch.