Links in 'Markdown cannot be installed' error message show as raw HTML

The problem is somewhere in this but the logic is so convoluted that I can't figure it out:

      $urlString = $url ? $url->toString() : NULL;
      $urlLink = !$cli && $url ? Link::fromTextAndUrl($url->toString(), $url)->toString() : $urlString;

Yeah, you can't put a rendered Link object in a @placeholder -- @ gets escaped!

      $urlLink = !$cli && $url ? Link::fromTextAndUrl($url->toString(), $url)->toString() : $urlString;
      return new FormattableMarkup($urlLink ? '@label: @reason (@url)' : '@label: @reason', [
        '@label' => $parser->getLabel(),
        '@reason' => $reason,
        '@url' => $urlLink,
      ]);

The HTML A element needs to be in the main part of the string, not in a placeholder replacement.

Same applies to this:

          '@reason' => $reason,

$reason contains an HTML A element!