At the beginning of chapter 5 I try to compile previously added code in chapter 4 and receive the following output:

Here's my Greeter.sol code:
`pragma solidity ^0.8.0;
import "@openzeppelin/contracts/access/Ownable.sol";
contract Greeter is Ownable {
string private _greeting = "Hello, World!";
address private _owner;
constructor() {
_owner = msg.sender;
}
modifier onlyOwner() {
require(
msg.sender == _owner,
"Ownable: caller is not the owner!"
);
_;
}
function greet() external view returns(string memory) {
return _greeting;
}
function setGreeting(string calldata greeting) external {
_greeting = greeting;
}
function owner() public view returns(address) {
return _owner;
}
} `