An error in the top-level encode.
- iOS 9.0+
- macOS 10.11+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 2.0+
The meaning of this property depends on the setting of the
decoding property. For
NSCoder, this property is always
NSCoder, a non-
nil value represents the first error encountered while decoding the archive.