qBittorrent & operating system versions

qBittorrent: 4.6.3 x64
Operating system: Arch Linux x64
Qt: 5.15.12
libtorrent-rasterbar: 1:2.0.9

What is the problem?

WebUI seems to skimp on feedback when user tries to add an invalid or semi-invalid download source. If an invalid torrent or magnet or even just some of them (when multiple are involved) are added, WebUI is just silent about it and for example doesn't inform the user that one of the added torrents was corrupt.

A somewhat similar case of a semi-invalid download is when a duplicate torrent/link with or without additional trackers is being added. WebUI should probably at least inform the user about the number of newly-extracted tracker URLs to indicate something was just done (which it currently doesn't).

Possibly related: #10960, #12650

Steps to reproduce

1. Try to add an invalid torrent or a magnet link through the WebUI. For demonstration purposes you can also input just a single character as a magnet link.
2. Confirm adding the torrent/link.
3. Nothing happens, and the WebUI doesn't even indicate anything.
4. Also try to add a torrent/magnet that is already being downloaded, but with additional trackers (or not).
5. qBittorrent will extract additional tracker information (or not), but again not indicate anything.

Additional context

No response

Log(s) & preferences file(s)

No response