Continued from "Nothing is available, is anything?" Tag questions for negative sentences ---
John: Finally I got a reply from the e-gov sysadmin! They say the system is "experiencing a technical issue" now.
Paul: So there was nothing wrong with your submission...
- Of course! How could it be wrong?
- Of course not! How could it be wrong?
Which of them is correct?
How about "nowhere," "nobody," or "none of them" etc? Should I use "of course" or "of course not" to confirm the statement?