alt Hacker News> For optional types, 0 is decoded as the default value of the underlying type (e.g. string? decodes 0 as "", not null).
In the "dense JSON" format, isn't representing removed/absent struct fields with `0` and not `null` backwards incompatible?
If you remove or are unaware of a `int32?` field, old consumers will suddenly think the value is present as a "default" value rather than absent
That is correct and that is a good catch, the idea though is that when you remove a field you typically do that after having made sure that all code no longer read from the removed field and that all binaries have been deployed.