foreach my $some_path ( (defined $path_list &&
                         $#$path_list >= 0)
                         ? @{$path_list} : "" ) {

clean_path($some_path); # $some_path is now ""

## i'd rewrite it as
foreach my $some_path ( (defined $path_list and
                         ref($path_list) eq 'ARRAY'
                         and scalar @{$path_list} )
                         ? @{$path_list} : '') {