Special folder handling for FastMail: warnings + some folders not loading

I’m not entirely sure what I’m doing with the special folders mapping (I basically followed the example in the Yahoo mappings and adapted them to FastMail).

This is the console dump when I start Geary:

Gtk-Message: 21:09:11.384: GtkDialog mapped without a transient parent. This is discouraged.
![crt] 21:11:48 156.998743 geary: geary_endpoint_get_tls_validation_warnings: assertion 'GEARY_IS_ENDPOINT (self)' failed
![crt] 21:11:48 0.000006 geary: geary_endpoint_get_tls_validation_warnings: assertion 'GEARY_IS_ENDPOINT (self)' failed
![crt] 21:11:48 0.000008 geary: geary_endpoint_get_tls_validation_warnings: assertion 'GEARY_IS_ENDPOINT (self)' failed
![crt] 21:11:48 0.000004 geary: geary_endpoint_get_tls_validation_warnings: assertion 'GEARY_IS_ENDPOINT (self)' failed
*[wrn] 21:13:23 95.441223 geary: imap-engine-generic-account.vala:1313: Unable to ensure special folder GEARY_SPECIAL_FOLDER_TYPE_SENT: Server reports error creating folder /Sent: a015 NO [USEATTR] SPECIAL-USE flag conflict
*[wrn] 21:13:23 0.306002 geary: imap-engine-generic-account.vala:1313: Unable to ensure special folder GEARY_SPECIAL_FOLDER_TYPE_SPAM: Server reports error creating folder /Junk: a016 NO [USEATTR] SPECIAL-USE flag conflict
*[wrn] 21:13:24 0.306028 geary: imap-engine-generic-account.vala:1313: Unable to ensure special folder GEARY_SPECIAL_FOLDER_TYPE_ARCHIVE: Server reports error creating folder /Archive: a017 NO [USEATTR] SPECIAL-USE flag conflict
*[wrn] 21:20:04 400.438992 geary: sidebar-tree.vala:209: Entry FolderEntry: aral@ind.ie not found in sidebar

Also, not all folders appear after account setup.

Just as I wrote that, I launced Geary again to take a screenshot for this report and the rest of the folders appeared also and, on second launch, I am not getting the warnings/dump. I will test further once I figure out how to remove the account.