This is a warning from Perl indicating that an empty value was found where one is expected. The warning is left in so that you know that something is missing.
Whatever it is, it can be found at the specified ``chunk'', or line, of catalog.cfg -- if you use the #include capability, it would have to be factored in as well.
The usual reason is that a file is specified in one of the directives (usually one of Help SearchProfile OrderProfile Buttonbars UpsZoneFile) and does not exist. See the documentation for the directive on how the file name should be specified.
<H3> Mini-FAQ: Why isn't the error more enlightening?</H3>
Because Perl won't tell us what exactly went wrong -- see it's FAQ for why.