cursed NFT which can not be transfered

MyNFT4.sol

// SPDX-License-Identifier: GPL-3.0

pragma solidity >=0.7.0 <0.9.0;

import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC721/ERC721.sol";
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/Strings.sol";
import "https://github.com/Brechtpd/base64/blob/main/base64.sol";

contract MyNFT4 is ERC721 {

    bool public lock = false;
    address owner;
    uint public nextTokenId = 0;

    constructor() ERC721("Cursed NFT2", "CNFT"){
        owner = msg.sender;
    }

    function mint() public {
        uint256 tokenId = nextTokenId;
        nextTokenId = nextTokenId + 1;
        super._safeMint(msg.sender, tokenId);
    }

    function _transfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual override {
        //lock=trueのとき、自分宛(ミント時)以外は持ち主変更はエラーにする
        if(to != msg.sender){
            //revert("can not trasfer!");
            require(!lock, "can not transfer!");
        }
        super._transfer(from, to, tokenId);
    }

    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
        string memory svg = getSvg(tokenId);
        bytes memory json = abi.encodePacked(
            '{"name": "#'
            ,Strings.toString(tokenId)
            ,'", "description": "this NFT can not be transfer!", "image": "data:image/svg+xml;base64,'
            ,Base64.encode(bytes(svg))
            ,'", "attributes": [{"value": "Cursed"}]'
            ,'}'
        );
        return string(abi.encodePacked("data:application/json;base64,", Base64.encode(json)));
    }

    function getSvg(uint tokenId) public pure returns (string memory) {

        return string(abi.encodePacked(
            '<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64">'
            ,'<rect width="100%" height="100%" fill="#000000" />'

            ,'<text x="10%" y="70%" font-size="50px" fill="#ffffff">'
            ,string(unicode"呪")
            ,'</text>'

            ,'<text x="10%" y="90%" font-size="8px" fill="#ffffff">'
            ,string(unicode"(非売品) #")
            ,Strings.toString(tokenId)
            ,'</text>'

            ,'</svg>'
        ));
    }

    function setTransferLock(bool _lock) public {
        require (owner == msg.sender);
        lock = _lock;
        emit LockEvent(lock);
    }

    event LockEvent(bool _lock);

}