Sending ERC20 tokens using the transfer function

Question

I'm pretty new to programing in solidity and I'm currently trying to run a simple smart contract in Remix, seen bellow:

pragma solidity ^0.8.0;

import "github.com/OpenZeppelin/openzeppelin-contracts/contracts/token/ERC20/utils/SafeERC20.sol";

contract Swap  {
    address public owner;
    uint256 public balance;
    
    event TransferReceived(address _from, uint _amount);
    event TransferSent(address _from, address _destAddr, uint _amount);
    
    constructor() {
        owner = msg.sender;
    }
    
    receive() payable external {
        balance += msg.value;
        emit TransferReceived(msg.sender, msg.value);
    }    
    
    function withdraw(uint amount, address payable destAddr) public {
        require(msg.sender == owner, "Only owner can withdraw funds"); 
        require(amount <= balance, "Insufficient funds");
        
        destAddr.transfer(amount);
        balance -= amount;
        emit TransferSent(msg.sender, destAddr, amount);
    }
    
    function transferERC20(IERC20 token, address to, uint256 amount) public {
        require(msg.sender == owner, "Only owner can withdraw funds"); 
        uint256 erc20balance = token.balanceOf(address(this));
        require(amount <= erc20balance, "balance is low");
        token.transfer(to, amount);
        emit TransferSent(msg.sender, to, amount);
    }    
}

While I can successfully send BNB and call the withdraw function giving the value sent and my wallet address in the BSC testnet, I'm having issues when running the transferERC20 function. The only output that I get when calling this method is the following message:

Gas estimation errored with the following message (see below). The transaction execution will likely fail. Do you want to force sending? Internal JSON-RPC error. { "code": -32000, "message": "execution reverted" }

I've tried several different addresses that I found in the testnet.bscscan website for BNB while making sure that the contract had enough funds for transfering, but I had no success.

Can someone suggest what might be going wrong in my contract/setup? Am I making this transfer properly?

Answer 1

• fix constrcutor

  constructor() {
        // payable allows payment of ether with a call.
        owner = payable(msg.sender);
    }
  

• make sure those require statements are satisfied

    require(msg.sender == owner, "Only owner can withdraw funds"); 
    require(amount <= balance, "Insufficient funds");
  

• check that you are connected to correct network