The error handling for loading errors on albums, non-album tracks and files is currently all very different:

• Albums show errors in info dialog, tracks and files not
• In itemviews tracks show error as tooltip, albums show a general message (since PICARD-2035), files show nothing
• Albums can potentially handle multiple errors (e.g. due to plugins), tracks and files not
• If an album shows errors, the normal info tab in info dialog is hidden

This should all be unified and errors been shown in a separate tab of the entities info dialog.