No incorrect message appears when adding a wrong Captcha

Steps to reproduce:

1. Access Administer Wiki
2. Click on Other > CAPTCHA
3. Select Type > Image / Sound / Text
4. Select one of the Engine
5. Click on the Save button
6. Click on Users & Rights > Registration
7. Tick "Require CAPTCHA to register"
8. Save the changes
9. Log out of the wiki
10. Click on Drawer > Register
11. Complete the fields
12. Add a wrong CAPTCHA
13. Click on Register

Expected results: A message appears letting the user know that the CAPTCHA is wrong.

Actual results: No message appears, the page is just refreshed.

Note: Issue also reproduces on 11.0.1 Standard