ERC20InsufficientAllowance in ERC20Wrapper Contract

Question

I got this error:

ERC20InsufficientAllowance
Parameters:
{
 "spender": {
  "value": "0xb31BA5cDC07A2EaFAF77c95294fd4aE27D04E9CA",
  "documentation": "Address that may be allowed to operate on tokens without being their owner."
 },
 "allowance": {
  "value": "0",
  "documentation": "Amount of tokens a `spender` is allowed to operate with."
 },
 "needed": {
  "value": "10",
  "documentation": "Minimum amount required to perform a transfer."
 }
}
You may want to cautiously increase the gas limit if the transaction went out of gas.

My Contract:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.23;

import "@openzeppelin/contracts/token/ERC20/extensions/ERC20Wrapper.sol";

contract xBTCWrapper is ERC20, ERC20Wrapper {
    IERC20 public  _underlying;

    constructor(IERC20 underlyingToken)
        ERC20("Wrapped xBTC", "wxBTC")
        ERC20Wrapper(underlyingToken)
    { 
        _underlying = underlyingToken;
    }

    function getUnderlyingBalance() public view returns(uint256) {
        return _underlying.balanceOf(_msgSender());
    }

    function decimals() public view virtual override(ERC20Wrapper, ERC20) returns (uint8) {
        return 18;
    }
}

Note I've tried to send it with only transfer but this time I got ERC20InsufficentBalance Error, which is weird because I've tokens.

using SafeERC20.transfer instead of transferFrom

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.23;

import "@openzeppelin/contracts/token/ERC20/extensions/ERC20Wrapper.sol";

contract xBTCWrapper is ERC20, ERC20Wrapper {
    IERC20 public  _underlying;

    constructor(IERC20 underlyingToken)
        ERC20("Wrapped xBTC", "wxBTC")
        ERC20Wrapper(underlyingToken)
    { 
        _underlying = underlyingToken;
    }

    function depositFor(address account, uint256 value) public virtual override(ERC20Wrapper) returns (bool) {
        address sender = _msgSender();
        if (sender == address(this)) {
            revert ERC20InvalidSender(address(this));
        }
        if (account == address(this)) {
            revert ERC20InvalidReceiver(account);
        }
        SafeERC20.safeTransfer(_underlying, address(this), value);
        _mint(account, value);
        return true;
    }

    function getUnderlyingBalance() public view returns(uint256) {
        return _underlying.balanceOf(_msgSender());
    }

    function decimals() public view virtual override(ERC20Wrapper, ERC20) returns (uint8) {
        return 18;
    }
}

The other error:

ERC20InsufficientBalance
Parameters:
{
 "sender": {
  "value": "0x7C4e30a43ecC4d3231b5B07ed082329020D141F3",
  "documentation": "Address whose tokens are being transferred."
 },
 "balance": {
  "value": "0",
  "documentation": "Current balance for the interacting account."
 },
 "needed": {
  "value": "10",
  "documentation": "Minimum amount required to perform a transfer."
 }
}
You may want to cautiously increase the gas limit if the transaction went out of gas.

Answer 1

You should use transferFrom. The "ERC20InsufficientAllowance" is because you need to approve the contract as spender in a previous transaction.