Yes, anything to warn of danger is good. You can check if the directory is not empty and say so, as I suggested. And make the warning more noticeable, as someone else suggested. One can always empty the calibre directory by hand. Or look at the files.
Before retired as an IT person, I was frequently reprimanded by younger people for not taking adequate precautions during installation. So don't think I'm blaming you personally. I am suggesting improvement, that's all.
And if I'm ticked off, it's with myself too. I never get as mad with anyone else as I do with myself when I make a mistake. I do have the right to be ticked off about losing my system.
So let's just admit it can be done better and profit from the occasion. After all, calibre is an extremely useful program and one which I am happy to have!
