"Something's gone wrong" deletes 20 minutes of editing a reply

I spent over 20 minutes editing a reply, and after clicking Send, I got the error message “Something’s gone wrong”, and all of the reply text has disappeared.  Thank you for respecting my time.

This problem is easy to reproduce.  Create a new reply and copy/paste the text from the attached file “buggy.txt” into the reply, then click Send. 

Adding a space before the open parentheses avoids the problem.  Shame on the developers.

The old Khoros platform saved your edits every few seconds and would recover them in situations like this.