If current disc isn't found, propose to use a new one or cancel
Migrated from https://bugzilla.gnome.org/show_bug.cgi?id=782291
When running a multi disc game and the image corresponding to the latest used disc can't be found an "Unexpected error" is displayed to the user.
We should instead propose the user to select another disc to run the game or to cancel to avoid loosing the current state of the game.