Remove unnecessary function can make the code simpler and save some gas

[code423n4]

Handle

WatchPug

Vulnerability details

https://github.com/code-423n4/2021-12-mellow/blob/6679e2dd118b33481ee81ad013ece4ea723327b5/mellow-vaults/contracts/AaveVault.sol#L96-L99

    function _getAToken(address token) internal view returns (address) {
        DataTypes.ReserveData memory data = _lendingPool().getReserveData(token);
        return data.aTokenAddress;
    }

https://github.com/code-423n4/2021-12-mellow/blob/6679e2dd118b33481ee81ad013ece4ea723327b5/mellow-vaults/contracts/AaveVault.sol#L33-L43

    constructor(IVaultGovernance vaultGovernance_, address[] memory vaultTokens_)
        Vault(vaultGovernance_, vaultTokens_)
    {
        _aTokens = new address[](vaultTokens_.length);
        for (uint256 i = 0; i < _vaultTokens.length; i++) {
            address aToken = _getAToken(_vaultTokens[i]);
            require(aToken != address(0), ExceptionsLibrary.ZERO_TOKEN);
            _aTokens[i] = aToken;
            _tvls.push(0);
        }
    }

_getAToken() is unnecessary as it's being used only once. Therefore it can be inlined in constructor() to make the code simpler and save gas.

Recommendation

Change to:

    constructor(IVaultGovernance vaultGovernance_, address[] memory vaultTokens_)
        Vault(vaultGovernance_, vaultTokens_)
    {
        _aTokens = new address[](vaultTokens_.length);
        for (uint256 i = 0; i < _vaultTokens.length; i++) {
            address aToken = _lendingPool().getReserveData(_vaultTokens[i]).aTokenAddress;
            require(aToken != address(0), ExceptionsLibrary.ZERO_TOKEN);
            _aTokens[i] = aToken;
            _tvls.push(0);
        }
    }