title: mpdf no output and php errors in mpdf.php
body: <p>I'm trying to generate a pdp file in a cakephp application. Therefore, I use the mpdf library as a vendor. But when I try to make a even very simple output it doesn't work. Then when I use the debug property, it shows php errors in the mpdf.php file.</p>
  
  <p>Here is my source code:</p>
  
  <pre><code>&lt;?php
  $mpdf=new mPDF();
  $mpdf-&gt;WriteHTML('hello');
  $mpdf-&gt;debug = true;
  $mpdf-&gt;Output();
  exit;
  ?&gt;
  </code></pre>
  
  <p>And these are the errors shown in the browser:</p>
  
  <p>Notice (8): Undefined index: BODY [APP\vendors\MPDF54\mpdf.php, line 14242]</p>
  
  <p>Notice (8): Undefined index: BODY>>ID>> [APP\vendors\MPDF54\mpdf.php, line 14288]</p>
  
  <p>Notice (8): Undefined offset: -1 [APP\vendors\MPDF54\mpdf.php, line 14421]</p>
  
  <p>Thank you for your help!</p>