Fallback.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10; // Latest solidity version

import 'openzeppelin-contracts/contracts/utils/math/SafeMath.sol'; // Path change of openzeppelin contract

contract Fallback {

  using SafeMath for uint256;
  mapping(address => uint) public contributions;
  address payable public owner;

  constructor() public {
    owner = payable(msg.sender); // Type issues must be payable address
    contributions[msg.sender] = 1000 * (1 ether);
  }

  modifier onlyOwner {
        require(
            msg.sender == owner,
            "caller is not the owner"
        );
        _;
    }

  function contribute() public payable {
    require(msg.value < 0.001 ether, "msg.value must be < 0.001"); // Add message with require
    contributions[msg.sender] += msg.value;
    if(contributions[msg.sender] > contributions[owner]) {
      owner = payable(msg.sender); // Type issues must be payable address
    }
  }

  function getContribution() public view returns (uint) {
    return contributions[msg.sender];
  }

  function withdraw() public onlyOwner {
    owner.transfer(address(this).balance);
  }

  
  fallback() external payable { // naming has switched to fallback
    require(msg.value > 0 && contributions[msg.sender] > 0, "tx must have value and msg.send must have made a contribution"); // Add message with require
    owner = payable(msg.sender); // Type issues must be payable address
  }
}