Gas Optimizations

[code423n4]

State variable COW_SETTLEMENT and COW_RELAYER declared in StakingStorage could be declared as constant

COW_SETTLEMENT and COW_RELAYER are initialized in Staking.sol initialize function with a constant address.

The initialization of those variable could be moved directly in their definition and transform those variables in constants, optimizing the gas usage for portion of code that use them.

Staking _sendAffiliateFee should avoid sending fee when the amount is zero

feeAmount in _sendAffiliateFee could be zero because of rounding if (_amount * affiliateFee) < BASIS_POINTS.

The function could check feeAmount > 0 and perform IERC20Upgradeable(TOKE_TOKEN).safeTransfer(FEE_ADDRESS, feeAmount) only in that case

Staking transferToke should avoid sending Toke when the amount is zero

If totalTokeAmount is equal to zero, avoid to call safeTransfer and waste gas sending 0 transferring zero tokens.