Missing zero address checks in NiftyKitV3.sol

Informational

    function initialize(address appRegistry_) public initializer {
        _appRegistry = appRegistry_;
        _treasury = _msgSender();
        __Ownable_init();
    }

    function setTreasury(address newTreasury) external onlyOwner {
        _treasury = newTreasury;
    }

    function setSigner(address signer) external onlyOwner {
        _signer = signer;
    }

These function don't check that the input address is not zero. It's better not to be able to set a 0 address, than to discover that it has been set by error.

Recommendation

Add zero-address check to these functions.