Steps to reproduce:
- Open two questions (with answers, in this case) in different tabs in the same browser
- Flag an answer to one (might not be needed, but it's what I did, so I'm including it)
- Someone else (might need a diamond for this) deletes an answer to the other
- Without reloading the second tab, try opening the flag dialog on the now deleted answer
Environment: Firefox 46.0.1 on up-to-date Windows 8.1.
Actual result: The UI responds with a message stating that I am opening the flag dialog too quickly.
Expected behavior: (A) The flag dialog should open, as happens after I reload the page and click "flag" again. Alternatively, (B) a message should be displayed saying that the answer is ineligible for flagging. If the user doesn't have the reputation necessary to see deleted posts, always do (B).
Something like this, shamelessly borrowed from this answer by cybermonkey: