Solidity: Custom Error Message in require() Not Showing

Remix supports it.

in a code i am working on for require(stuff..,"player doesn't exist"); i get in the console the message:

Reason provided by the contract "player doesn't exist"

You can use Strings.sol library about OpenZeppelin and strings.sol about Arachnid to concatenate strings and build your message.

You can see this example:

// SPDX-License-Identifier: MIT
pragma solidity 0.8.0;

import "https://github.com/Arachnid/solidity-stringutils/blob/master/src/strings.sol";
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/Strings.sol";

contract Test {
    using Strings for *;
    using strings for *;
    address owner;

    constructor() {
        owner = msg.sender;
    }

    modifier onlyOwner() {
        require(msg.sender == owner, getMessage(msg.sender, owner));
        _;
    }

    function test() public onlyOwner {
        // TODO: your logic
    }

    function getMessage(address _callingAddress, address _owner) private returns(string memory){
        // Convert Address to String
        string memory _ownerAddress = Strings.toHexString(uint160(uint160(_owner)));
        string memory _calledAddress = Strings.toHexString(uint160(uint160(_callingAddress)));
        // Define two pieces about message
        string memory _firstMessage = "Owner mismatch: ".toSlice().concat(_ownerAddress.toSlice());
        string memory _secondMessage = " != ".toSlice().concat(_calledAddress.toSlice());
        // Concat in one message
        string memory _message = _firstMessage.toSlice().concat(_secondMessage.toSlice());
        return _message; 
    } 
}

UPDATED ANSWER:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/Strings.sol";

contract Test {
    using Strings for *;
    address owner;

    constructor() {
        owner = msg.sender;
    }

    modifier onlyOwner() {
        string memory _ownerAddress = Strings.toHexString(uint160(uint160(owner)));
        string memory _calledAddress = Strings.toHexString(uint160(uint160(msg.sender)));
        require(msg.sender == owner, string(abi.encodePacked( "Owner mismatch: ", _ownerAddress, " != ", _calledAddress)));
        _;
    }

    function test() public onlyOwner {
        // your logic
    }
}