pub fn get_extra(&self) -> B {
        match B::deserialize(&self.extra.state) {
            Ok(extra) => extra,
            // This should never happen...
            Err(err) => panic!(
                "unrecoverable extra build state extraction failure: {:#?}",
                err
            ),
        }
    }
Get the extra build state as an owned type.

# Panics
Hypothetically, if there were a failure in the Perseus core such that
your extra build state ended up being malformed, this would panic.
However, this should never happen, as there are multiplr layers of
checks before this that should catch such an event. If this panics,
and if keeps panicking after `perseus clean`, please report it as a
bug (assuming all your types are correct).
packages/perseus/src/state/state_generator_info.rs