Steps to Reproduce:
Open a talk page with DT enabled
Click the reply link after a comment
Click 'Reply' to post a reply without adding to the comment
Actual Results:
The reply is posted (https://en.wikipedia.beta.wmflabs.org/w/index.php?title=User_talk:RhinosF1&diff=414359&oldid=414152)
Expected Results:
A confirmation dialog appears or the edit is disallowed as there is very few times where an empty reply is needed.