Not all IERC20 implementations revert() when theres a failure in transfer()/transferFrom(). The function signature has a boolean return value and they indicate errors that way instead. By not checking the return value, operations that should have marked as failed, may potentially go through without actually making a payment
There are 4 instances of this issue:
https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/Basket.sol#L87
https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/Basket.sol#L94
https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVault.sol#L517
https://github.com/code-423n4/2022-06-nibbl/blob/8c3dbd6adf350f35c58b31723d42117765644110/contracts/NibblVault.sol#L526
