Bad code

Hey. Faced a problem, when creating a new post, instead of a redirect, the Internal Server Error 500.
For a long time I figured out the problem of why it works on one host, and on the second, a copy of 100% does not work.

Explain why this piece of code is needed?
plugins / wp-user-frontend / includes / class-frontend-form-post.php
Lines: 470 – 472

$ dom = new DOMDocument ();
@ $ dom-> loadHTML ($ postarr [‘post_content’]);
$ images = $ dom-> getElementsByTagName (‘img’);

They created a problem for me