Hello, I have a problem with calling the WETH's withdraw function inside a Hardhat test

Here's my mock WETH, Auction and IWETH contracts: https://gist.github.com/talentlessguy/8a62bf05a03ea5973545b44c57945a41

Whenever _handleOutgoingBid is called, I recieve this error

Error: VM Exception while processing transaction: reverted with reason string 'ETH_TRANSFER_FAILED'
at MockWETH.permit (@rari-capital/solmate/src/tokens/ERC20.sol:128)
at MockWETH.withdraw (@rari-capital/solmate/src/tokens/WETH.sol:29)

when I tried w/ Zora's Mock WETH, it returned such error: function selector was not recognized and there's no fallback function

what am I doing wrong and where?