#2 Misleading error if iTunes couldn't find audio file

If Clutter tells iTunes to play an audio file that's in the library, but
iTunes can't find the file (sometimes it mysteriously forgets where
the file is) Clutter displays a misleading "Couldn't communicate
with iTunes" error message. It should show something more
meaningful, like "iTunes couldn't find the file".

This probably requires returning more detailed error information
from the AppleScripts.