Urls like https://doc.wikimedia.org/cover/visualeditor/ fail if navigated to without a trailing slash, like https://doc.wikimedia.org/cover/visualeditor.
This looks like it might be a configuration error on the doc.wm.o Apache, or missing a common default we normally enable on static servers.
This is particularly common to see because our publish jobs produce a clickable link without trailing slash.
E.g. at https://integration.wikimedia.org/ci/job/publish-to-doc1001/1810/console
+ rsync --archive --compress --delete-after . rsync://doc1001.eqiad.wmnet/doc/cover/visualeditor
Published at https://doc.wikimedia.org/cover/visualeditor
Done.
That could be fixed separately, but it'd be nice for general address-bar usability if things worked as expected when typing /cover or /cover/something