Add mailto link on 500 error page.
<div id="main-content">
<h2>Internal server error</h2>
<p>Something went wrong.</p>
+ <p>Please <a href="mailto:wikipedialibrary@wikimedia.org?Subject=Wikipedia%20Library%20Server%20Error">contact us about this error at wikipedialibrary@wikimedia.org</a>.</p>
<img src="500-dog.jpeg" class="img-responsive">
<!-- photo via https://unsplash.com/photos/NhRJJwzGRXQ under a CC0 license -->
</div>
