DownloadHandler.CompletionHandler called twice #57
Description
If a download via the download method in Client succeeds the completion handler is called twice:
The first call is triggered by downloadExecutor(_ downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL). The second by downloadExecutor(_ downloadTask: URLSessionDownloadTask, didCompleteWithError error: Error?) with error = nil.
Since download(url: URL, progressHandler: DownloadHandler.ProgressHandler, _ completion: @escaping DownloadHandler.CompletionHandler) offers a completion handler (and not some delegation), completion should only called once after the internal downloadTask has finished.