OK, I hit this thrice today itself.
I was trying to write a comment under a particular post. After composing I clicked on the submit button, a pop up is shown saying this post is deleted, locked or something else.
Should there be a pop up saying "No use of this comment. This post is a goner" or something English , when I am writing the comment itself. Why wait until user finishes the entire composition process? I can pack up and go to next question, without wasting a precious minute.
P.S : I see this, 3 year old question which is a feature request. It is neither status-completed and nor decined. It is somewhat related, but my suggestion is different. I couldn't find any other duplicates.