--- loncom/cgi/barcode.png	2001/08/15 14:03:15	1.2
+++ loncom/cgi/barcode.png	2001/09/28 20:26:02	1.3
@@ -32,12 +32,19 @@ Content-type: image/gif
 
 END
 
+unless(defined($ENV{'form.encode'}) and length($ENV{'form.encode'})) {
+    $ENV{'form.encode'}='***ERROR***UNDEFINED***';
+}
+
 my $oGdBar=GD::Barcode::Code39->new($ENV{'form.encode'});
-warn($GD::Barcode::errStr);
+if ($GD::Barcode::errStr or !defined($oGdBar)) {
+    warn($GD::Barcode::errStr);
+    $oGdBar=GD::Barcode::Code39->new('***ERROR***INVALID***');
+}
 my $bindata=$oGdBar->plot->png; # create barcode image
 undef $oGdBar;
 binmode(STDOUT);
-open OUT,"|pngtopnm|ppmtogif"; # convert into a gif image
+open OUT,"|pngtopnm|ppmtogif 2>/dev/null"; # convert into gif image
 print OUT $bindata; # output image
 $|=1; # be sure to flush before closing
 close OUT;