Saxon & Fallback from document() error ?

I'm looking to update files, who's name are suggested by input.xml.

However I get java FileNotFoundException if those files suggested doesn't
already exist.
(This from using Saxon for it's XSLT 2.0.)

Is there any way around this?
Ideally I need to know that the file doesn't exist or that it's empty.

I could only find suggestions this was a problem, and talk in 2001 'Fallback
from document() error' suggesting that a solution was needed and that the
error was optional/not required.

Regards
davidpbrown