Warning before overwriting a file

[nk9]

I just downloaded 10k results before running out of credits. I didn't know that's why the download had stopped prematurely; I made a mistake and used shodan download again to the same file to continue from where I had left off.

Result: the file of 10k results was replaced with an empty file. But it's gzipped, so at least it's small!

AAAAAnyway, it would have really been preferred if the CLI had complained before blowing away the initial multi-megabyte .gz.