Failing scarb build

[FabijanC]

Getting this on scarb build:

$ scarb build
   Compiling ex v0.1.0 (/home/fabijanc/pscott/flush_example/starknet/Scarb.toml)
error: Plugin diagnostic: Unknown derive `Option` - a plugin might be missing.
 --> /home/fabijanc/pscott/flush_example/starknet/src/authenticator.cairo:38:23
#[derive(Clone, Drop, Option)]
                      ^****^

warn: Unused import: `ex::authenticator::EthAddress`
 --> /home/fabijanc/pscott/flush_example/starknet/src/authenticator.cairo:1:33
use starknet::{ContractAddress, EthAddress, Store, SyscallResult};
                                ^********^

warn: Unused import: `ex::authenticator::Store`
 --> /home/fabijanc/pscott/flush_example/starknet/src/authenticator.cairo:1:45
use starknet::{ContractAddress, EthAddress, Store, SyscallResult};
                                            ^***^

warn: Unused import: `ex::authenticator::SyscallResult`
 --> /home/fabijanc/pscott/flush_example/starknet/src/authenticator.cairo:1:52
use starknet::{ContractAddress, EthAddress, Store, SyscallResult};
                                                   ^***********^

warn: Unused import: `ex::authenticator::SyscallResultTrait`
 --> /home/fabijanc/pscott/flush_example/starknet/src/authenticator.cairo:2:15
use starknet::SyscallResultTrait;
              ^****************^

warn: Unused import: `ex::authenticator::Authenticator::ContractAddress`
 --> /home/fabijanc/pscott/flush_example/starknet/src/authenticator.cairo:12:20
    use starknet::{ContractAddress, EthAddress};
                   ^*************^

warn: Unused import: `ex::authenticator::Authenticator::Strategy`
 --> /home/fabijanc/pscott/flush_example/starknet/src/authenticator.cairo:13:16
    use super::Strategy;
               ^******^

warn: Usage of deprecated feature `"deprecated_legacy_map"` with no `#[feature("deprecated_legacy_map")]` attribute. Note: "Use `starknet::storage::Map` instead."
 --> /home/fabijanc/pscott/flush_example/starknet/src/authenticator.cairo:17:19
        _commits: LegacyMap::<(felt252, EthAddress), bool>
                  ^*******^

error: could not compile `ex` due to previous error

My scarb version is: 2.8.2 (latest at the time of writing)

[pscott]

Probably has to do with scarb version because I'm running 2.6.5.

Given that you have found the source of the issue, I won't bother updating :p