If you add CGI::Carp module you should see the error in your browser. Like this ;

#!/usr/bin/perl -w
use strict;
use CGI ':standard';
use CGI::Carp 'fatalsToBrowser';

use Bio::Graphics;

print header,start_html;
print 'Hello there!<br/>Just testing.<br/>';
for my $i (0..9){
  print $i.'<br/>';
} 
print end_html;
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