If the form saves but fails due to validation issues, then the value of that field will be retained (which is one of the benefits of properly implementing setValue).

You can try it by setting the file limit size to something tiny and uploading a too-large file. The validation will pop up, but it should stay set against the form until removed and a valid file is added.

In the future we could add some validation failed behaviour, such as to delete all uploaded files and clear them, but I think I'll keep that out of this pull request for the time being.

I'll update the docs to explain how this works.