No test coverage for nonstandard ERC-20 tokens

The contract lacks test cases for nonstandard ERC20 tokens such as USDT. This oversight could lead to unexpected behavior when interacting with these tokens. Implementing compatibility tests for various token types, including nonstandard ones, is recommended to ensure the contract's reliability and functionality across different token implementations. Such testing would enhance the contract's robustness and user confidence by verifying its ability to handle a wide range of tokens securely.