Summary

There are redundant checks in the burn and mint functions.

Vulnerability Details

In the burn function, it checks _amount <= 0 and balance < _amount, and in the mint function, it checks _to == address(0) and _amount <= 0. These checks are unnecessary because similar checks are already performed in _burn and _mint functions, making them redundant. Below is the code from OpenZeppelin:
https://github.com/OpenZeppelin/openzeppelin-contracts/blob/19293f3ecdb20a7f44d54279b5c1ddbb84de4a2e/contracts/token/ERC20/ERC20.sol#L297-L302
https://github.com/OpenZeppelin/openzeppelin-contracts/blob/19293f3ecdb20a7f44d54279b5c1ddbb84de4a2e/contracts/token/ERC20/ERC20.sol#L282-L287
https://github.com/OpenZeppelin/openzeppelin-contracts/blob/19293f3ecdb20a7f44d54279b5c1ddbb84de4a2e/contracts/token/ERC20/ERC20.sol#L244-L272

Impact

Redundant checks result in unnecessary computations and gas consumption

Tools Used

Manual review

Recommendations

It is advisable to remove these redundant checks.