Temporal file is not deleted in case transfer cancelled or iterrupted

[donpui]

While transferring large files, application save in temporal file .tmp. If transfer is cancelled by user or is interrupted, temporal file is kept on disk and not deleted. Such temporal file has no usage, as currently you cannot repeat process and resume download.

This can be an issue for users as consumes disk space with temporal files.
In my particular case, 17 GB .tmp file was kept in ~/Library/Containers/com.leastauthority.destiny/Data/Documents folder and I had manually delete it. Additionally I have found few more tmp files.