CauldronFeeWithdrawer for SpellPower Staking

In the CauldronFeeWithdrawer contract the ErrNotRegistered error is unused.

Implement the corresponding cauldron validation in the withdraw function or remove the ErrNotRegistered error.

In the distribute function the treasury share of mim rewards is transferred to the feeCollector even if the feeCollector has not yet been assigned. This introduces the risk of sending the treasury fees to the zero address if the system is not initialized properly.

Consider changing the if (treasuryAmount > 0) validation to if (treasuryAmount > 0 && feeCollector != address(0)). Any mim left in the CauldronFeeWithdrawer contract after failing this check that should go to the treasury can be withdrawn with the execute function calling the mim contract directly.

In the CauldronFeeWithdrawer deployment script there is an unused _cauldronPredicate function.

Implement the use case for the _cauldronPredicate or consider removing it.

The CauldronFeeWithdrawer contract is a UUPS upgradeable contract, however there are contracts which are not upgradeable friendly which the CauldronFeeWithdrawer inherits from. The FeeCollectable and OwnableOperators contracts include storage variables that do not use namespaced storage nor include a storage gap at the end. As a result if an upgrade takes place and the storage layout of either of the FeeCollectable and OwnableOperators contracts is changed this can result in unexpected storage issues.

Since the FeeCollectable and OwnableOperators contracts are already used in tandem with other contracts which might be upgradeable, it is sensitive to update them and potentially accidentally change the storage layout of those proxy contracts in an unexpected way. Instead just note this behavior and exercise caution when initiating any upgrades.

In the CauldronFeeWithdrawer script there is no configuration of the staking contract.

Consider adding logic to configure the staking contract for the Arbitrum deployment of the CauldronFeeWithdrawer contract.

In the constructor for the CauldronFeeWithdrawer the _initializeOwner function is called, however it is unnecessary to assign an owner for the implementation contract. Furthermore the owner is assigned as the zero address in the deployment script, meaning that this function does not update any storage and instead merely emits the OwnershipTransferred event.

Remove the _initializeOwner call from the CauldronFeeWithdrawer constructor.