Browser doesn't warn if user leaves form page after validation errors

This happens on every form, but here is an example of steps to reproduce:

1. Sign in
2. Go to the branch where you have permissions to create topics
3. Fill only subject
4. Submit the form, you'll get validation errors
5. Refresh the page

Actual Results: the page gets refreshed, all data is lost
Expected Results: browser asks whether user is sure to leave the page because all data would be lost