extractor: Propagate libarchive errors when metadata is encrypted

Currently, when trying to extract password protected 7z/RAR archives
with encrypted file lists, the reported error message is "empty
archive".

This message is not helpful and may be confusing for users.

To fix this situation, propagate libarchive errors by swapping the
"empty archive" and "autoar_common_g_error_new_a" statements.

Fixes https://gitlab.gnome.org/GNOME/gnome-autoar/-/issues/26