No "on error" messages about archinstall_gui

[Torxed]

There's support for this in the code via the log function now, but there's no error log function currently. This is mainly a limitation in archinstall currently. So we'll need to implement a proper log-flow there, before we can pick up errors.

Once that is done, I suggest a huge popup that covers the screen with a blurred background, to make sure the user can not accidentally click on any subsequent steps until the error dialogue is confirmed and closed.