title: Can't locate output affecting HTML and file output
body: <p>Below are screenshots of the output within Chrome dev tools, and one of my controller methods.</p>
  
  <p>The second screenshot is of an empty controller that simply <code>die();</code>'s.</p>
  
  <p>The third is the controller that is outputting the second image.</p>
  
  <p><a href="https://i.stack.imgur.com/aFzrt.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/aFzrt.png" alt="Screenshot of HTML output"></a></p>
  
  <p><a href="https://i.stack.imgur.com/4hUCh.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/4hUCh.png" alt="Screenshot of blank output"></a></p>
  
  <p><a href="https://i.stack.imgur.com/NNJ6a.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/NNJ6a.png" alt="enter image description here"></a></p>
  
  <p>I've trawled all files in my app in an attempt to locate the cause of the erroneous output, with no success.</p>
  
  <p>It <em>appears</em> to be an accidentally commented <code>&lt;?php</code> tag, but I can't see how that would cause the doctype error?</p>
  
  <p>I should note that this is happening <em>globally</em>, and I've already checked my existing doctype declaration and opening php tags.</p>
  
  <p>At my wit's end, thanks for any help.</p>