SyncErrorCode:
| "E_HOST_KEY_MISMATCH"
| "E_TLS_CERT"
| "E_INSECURE_PROTOCOL"
| "E_AUTH"
| "E_PATH_UNSAFE"
| "E_MASS_DELETE"
| "E_EMPTY_ROOT"
| "E_STALE_ITEM"
| "E_CONFIG_INVALID"
| "E_SITE_NOT_FOUND"
| "E_SERVER_NOT_FOUND"
| "E_CREDENTIAL_STORE"
| "E_LOCKED"
| "E_CONNECTION"
| "E_TIMEOUT"
| "E_REMOTE"
| "E_REMOTE_ROOT"
| "E_LISTING_LIMIT"
| "E_ROOT_DELETE"
| "E_PLAN_INVALID"
| "E_CANCELLED"
Stable codes carried by every SyncError.