Optional ReadonlycertificateE_TLS_CERT: the certificate that did not verify.
Optional ReadonlyfoldersE_REMOTE_ROOT: up to 50 folder names in the starting folder.
Optional ReadonlyreasonE_AUTH: the server refused the sign-in, no source had a secret, or a saved secret was not sent because the server changed.
Optional ReadonlystartingE_REMOTE_ROOT: the folder the account opens in after signing in.
Facts about an error that a program can act on, beyond its code. Never holds a secret.