Crowdfunding smart contract (not tested)

BuskVault.sol

pragma solidity >=0.8.0 <0.9.0;

interface IERC20 {
  function totalSupply() external view returns (uint256);
  function balanceOf(address account) external view returns (uint256);
  function transfer(address recipient, uint256 amount) external returns (bool);
  function allowance(address owner, address spender) external view returns (uint256);
  function approve(address spender, uint256 amount) external returns (bool);
  function transferFrom(
    address sender,
    address recipient,
    uint256 amount
  ) external returns (bool);
  event Transfer(address indexed from, address indexed to, uint256 value);
  event Approval(address indexed owner, address indexed spender, uint256 value);
}

contract BuskVault {
  uint public constant goalAmount = ${goal};
  IERC20 public constant token = IERC20(${token});
  uint public constant start = ${start}; // Timestamp
  uint public constant end = ${end}; // Timestamp
  address public constant creator = ${creator};

  bool cancelled;
  uint balance;
  uint depositorCount;
  mapping(address => uint) depositors;

  event Deposit(address depositor, uint amount);
  event Withdrawal(address depositor, uint amount);
  event Cancelled();
  event Received();

  modifier onlyCreator() {
    require(msg.sender == creator, "Not authorized");
  }
  modifier onlyUnfinishedOrUnmet() {
    require(cancelled == true || block.timestamp < end || balance < goal,
      "Finished and Goal Met");
  }
  modifier onlyLive() {
    require(cancelled == false, "Cancelled Already");
    require(block.timestamp < end, "Ended Already");
  }

  function deposit(uint amount) external onlyLive {
    require(block.timestamp >= start, "Not Yet Started");
    require(amount > 0, "Cannot Deposit Zero");
    token.transferFrom(msg.sender, address(this), amount);
    if(depositors[msg.sender] == 0) {
      depositorCount++;
    }
    balance += amount;
    depositors[msg.sender] += amount;
    emit Deposit(msg.sender, amount);
  }
  function withdraw(uint amount) external onlyUnfinishedOrUnmet {
    require(amount > 0, "Cannot Withdraw Zero");
    require(depositors[msg.sender] >= amount, "Balance Insufficient");
    token.transferFrom(address(this), msg.sender, amount);
    if(depositors[msg.sender] == amount {
      depositorCount--;
    }
    depositors[msg.sender] -= amount;
    balance -= amount;
    emit Withdrawal(msg.sender, amount);
  }
  function withdrawAll() external {
    uint memory senderBalance = depositors[msg.sender];
    withdraw(senderBalance);
  }
  function cancel() external onlyCreator onlyLive {
    cancelled = true;
    emit Cancelled();
  }
  function receive() external onlyCreator {
    require(cancelled == false, "Cancelled Already");
    require(block.timestamp >= end, "Not Yet Finished");
    require(balance >= goal, "Goal Not Met");
    token.transferFrom(address(this), creator, balance);
    emit Received();
  }
}