Adding an answer containing a line break near the beginning breaks further comments operations

Steps to reproduce:
1) Create a new topics
2) Post an answer, that looks like this:

Hello,
This is my anwser, blabla

3) Post a comment on that answer (=> first issue)
4) Delete the comment posted (=> second issue)

Expected results:
For both 3) and 4), after proceeding to the operation, a redirection to the updated topic page is made, as with any other comment on answers

Current results:
For 3), after proceeding to comment creation, a redirection to a blank page happen
For 4), after proceeding to comment deletion, a redirection to a page showing html code happen