While I was using Snow Leopard, I've used many times the following pattern when creating my Applescripts:
on run args
set filePath to POSIX file (item 1 of args) as alias
...
end run
After upgrading to Mountain Lion, the above script seems to produce a warning, though:
2012-08-10 15:12:12.305 osascript[54131:303]
CFURLGetFSRef was passed this URL which has no scheme
(the URL may not work with other CFURL routines): path/to/input/file.ext
Could anyone enlighten on the meaning of the error?