I am using Carp along with Twig.PM, and I receive this error message, when using parsefile:
Missing base argument at /usr/lib/perl5/site_perl/5.6.0/HTTP/Request.pm line 107
As a test, I try parsing a simple segment of XML with parse, and receive this message:
Can't use string ("<doc><para>para1</para></doc>") as a symbol ref while "strict refs" in use at /usr/lib/perl5/site_perl/5.6.0/i386-linux/XML/Parser/Expat.pm line 456.

These errors only occur when Carp is turned on. Twig itself continues to work despite the error messages. Here's the code:

# aidbrowser.pm

package aidbrowser;
use CGI;
use XML::Twig;

BEGIN
{
$allaids = "FindingAids/";

%FullNames =
  (
     "UMASS"                    => "University of Massachussetts",
     "Smith"                    => "Smith College",
     "MtHolyoke"                => "Mt. Holyoke College",
     "Amherst"                  => "Amherst College",
     "Hampshire"                => "Hampshire College",
     "MortimerRareBookRoom"     => "Mortimer Rare Book Room, Smith Col
+lege",
     "SophiaSmithCollection"    => "Sophia Smith Collection, Smith Col
+lege"
  );
return bless( { }, shift);
}

sub printDirs()
{
   my $rets;
   my $content;
   opendir(THISDIR, $allaids) or die ("Couldn't open finding aids for 
+browsing!");
   my @dircontents = grep !/^\./, readdir THISDIR;
   closedir(THISDIR);
   foreach $content (@dircontents)
   {
      if(-e $allaids.$content && -d $allaids.$content)
      {
          if($FullNames{$content})
          {
             $rets .= p(h2($FullNames{$content}),br,printAids($content
+));
          }    
      }
   }
   return $rets;
}

sub printAids()
{
   my $aiddir = shift;
   my $eadid,$eadtitle,$eadauthor,$eadlastchng;
   opendir(AIDDIR, $allaids.$aiddir."/");
   my @dircontents = grep !/^\./, readdir AIDDIR;
   closedir(AIDDIR);
   my $rets;
   if(!@dircontents)
   {
      $rets .= em("No finding aids for this institution are available 
+at this time.");
   } 
   else
   {
      foreach $aid (@dircontents)
      {
        if($aid =~ /(\w+).xml/)
        {
           $eadid = $1;
           $rets .= p($eadid);
           $eadtitle = getAidTitle($allaids.$aiddir."/".$aid);
           $rets .= p("Title is $eadtitle");
        }
      }
   }
   return $rets;
}

sub getAidTitle()
{
   my $file = shift;
   my $twig = new XML::Twig();
   $twig->parsefile($file);
   $elt = $twig->get_xpath("//titleproper",0) or "No title";
   $elt = $twig->get_xpath('/ead/eadheader/filedesc/titlestmt/titlepro
+per',0) or "Invalid title";
   $text = $elt->text;
   $text=~ s/(^\s*|\s*$)//g;
   return $text;
}


sub browsingMenu()
{
   return h1("Select a finding aid to open"), printDirs();
}
1;
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