Steps to reproduce:

1. Enable Developer level debugging and display of messages on the WWW page.
2. Create a course using a core course format such as Topics.
3. Add Section links block (after making sure the block is enabled)
4. Change course format from Topic to Collapsed topics
5. Section links block displays the list of topics (incl. titles if configured as such), but the final Link to current topic is missing. In addition Debugger throws this error / notice:

 Notice: Undefined variable: linktext in /ocfs2/www/test39/blocks/section_links/renderer.php on line 76

(The notice is hidden under the top nav bar, so must be hidden using browser dev tools.)