Corrupt Download Catcher

When you download a file the browser will prompt you where to save it and will proceed as such. However, if the file doesn't exist on the server and the server returns an HTTP 404 error, the browser won't tell you and will just download that error page and save it as the file you wanted.

Only afterwards when you try to open the file will you realize it is not what you wanted.

This add-on will perform 2 checks to make sure the file is the one you wanted:

* If the downloaded file is less than 4 KB it will show a notification telling you so. A file less than 4 KB should rarely happen.

* If the file download request was responded to with a 4XX or a 5XX error, it will also show a notification telling you so.