Dummy smart contract used for reproducing a Buidler bug

Counter.sol

// SPDX-License-Identifier: LGPL-3.0-or-later

pragma solidity ^0.6.8;

contract Counter {
    uint256 public count = 0;

    event CountedTo(uint256 number);

    function countUp() public returns (uint256) {
        uint256 newCount = count + 1;
        require(newCount > count, "Uint256 overflow");

        count = newCount;

        emit CountedTo(count);
        return count;
    }

    function countDown() public returns (uint256) {
        uint256 newCount = count - 1;
        require(newCount < count, "Uint256 underflow");

        count = newCount;

        emit CountedTo(count);
        return count;
    }
}