The link doesn't exist in the English version and it doesn't work
anymore because appending a parameter to a link doesn't work when the
link is not just a URL but an HTML link

When loading plugins, $lang might not be initialized yet, so use a
hardcoded error message instead, especially as this error should only be
displayed for the admin (and then fixed). This also removes the
previously localized message, it might be re-added as part of the new
extension manager.