Suppress libxml errors in DOMDocument::loadHTML() calls

[Copilot]

DOMDocument::loadHTML() emits warnings when parsing HTML fragments with malformed or mismatched tags, particularly in nested list structures with specific whitespace patterns.

Changes

Wrapped all loadHTML() calls with libxml_use_internal_errors() to suppress warnings while preserving previous error handling state:

• ListDiffLines.php: listByLines() and setInnerHtml() methods
• TableDiff.php: createDocumentWithHtml() method

$previousState = libxml_use_internal_errors(true);
$dom->loadHTML($html);
libxml_clear_errors();
libxml_use_internal_errors($previousState);

Added test fixture nested-list-warning.html reproducing the reported scenario.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• https://api.github.com/repos/doctrine/cache/zipball/56cd022adb5514472cb144c087393c1821911d09
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• https://api.github.com/repos/ezyang/htmlpurifier/zipball/b287d2a16aceffbf6e0295559b39662612b77fcf
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• https://api.github.com/repos/sebastianbergmann/object-enumerator/zipball/5c9eeac41b290a3712d88851518825ad78f45c71
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• https://api.github.com/repos/sebastianbergmann/object-reflector/zipball/b4f479ebdbf63ac605d183ece17d8d7fe49c15c7
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• https://api.github.com/repos/sebastianbergmann/resource-operations/zipball/05d5692a7993ecccd56a03e40cd7e5b09b1d404e
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• https://api.github.com/repos/sebastianbergmann/type/zipball/75e2c2a32f5e0b3aef905b9ed0b179b953b3d7c7
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• https://api.github.com/repos/sebastianbergmann/version/zipball/c6c1022351a901512170118436c764e473f6de8c
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If you need me to access, download, or install something from one of these locations, you can either:

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Original prompt

---

This section details on the original issue you should resolve

<issue_title>Warning: DOMDocument::loadHTML(): Unexpected end tag : u in Entity</issue_title>
<issue_description>We sometimes get this "Unexpected end tag" problem, and this is how to reproduce it. The following PHP file is very sensitive to spaces, so make sure each and every space is copied correct.y The above warning seems to go away when we use the "keep new lines" config option and remove all the spaces.

<html>

<p>This code fails.  To get it working, remove one space before the "ol" tag on line 31, which is just under "...Something here..." in $newHtml</p>

<?php

$oldHtml = '<ol>
        <li><u>Publication:</u>
          <ol>
            <li>This sentence.</li>
          </ol>
        </li>
        <li><u>Something here</u>:
          <ol>
            <li>Another item</li>
          </ol>
        </li>
      </ol>
      <ol>
        <li><u>Mars</u>:</li>
        <li>Saturn</li>
      </ol>';

      $newHtml = '<ol>
    <li><u>Publication:</u>
     <ol>
     <li>This sentence.</li>
     </ol>
     </li>
     <li><u>Something here</u>:
      <ol>
      <li>Another item</li>
      </ol>
      </li>
      <li><u>Mars</u>:
      <ol>
      <li>Saturn</li>
      </ol>
      </li>
    </ol>';

error_reporting(E_ALL);
ini_set('display_errors', '1');

require __DIR__ . '/../vendor/autoload.php';

use Caxy\HtmlDiff\HtmlDiff;
use Caxy\HtmlDiff\HtmlDiffConfig;

$config = new HtmlDiffConfig();
$config->setKeepNewLines(true);

$htmlDiff = HtmlDiff::create($oldHtml, $newHtml, $config);
$content = $htmlDiff->build();

echo "Diff is " . $content;

?>

</html>
```</issue_description>

## Comments on the Issue (you are @copilot in this section)

<comments>
<comment_new><author>@jschroed91</author><body>
@MykhailoSukovitsyn If you get a PR open for this, we will review and merge</body></comment_new>
</comments>

• Fixes Warning: DOMDocument::loadHTML(): Unexpected end tag : u in Entity #118

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