useless use of private variable in void context at CustomConfig.p m line 475...?

[Furnish, Trever G]

If I do:

perl -cw CustomConfig.pm

...then I get:
private variable in void context at CustomConfig.pm2 line 475.

The line numbers may have changed a little bit, but here's the tidbit of
code in question:
    # Use the sanitised filename to avoid problems caused by people forcing
    # logging of attachment filenames which contain nasty SQL instructions.
    $file = $message->{file2safefile}{$file} or $file;

Looking at that though I'm not sure whether it's really a problem or not.
So... any MS+Perl guru care to say whether that is something that needs
fixing?  I just adapted the SQLLogging code to work with flat files instead
(not enough spare mem on the test system to run mysqld :-( ) and inherited
this line in the process.

--
Trever