title: Unsupported operand types in file.php on line 266
body: <p>When I run my website, I see this error:</p>
  <pre><code>Unsupported operand types in file.php on line 266
  </code></pre>
  <p>Line 266 <code>file.php</code> is as the following:</p>
  <pre><code>$template_hook += $SetTemplates;
  </code></pre>
  <p>PHP version is 5.6.</p>