approve()/safeApprove() may revert if the current approval is not zero

[hats-bug-reporter]

Github username: @saidqayoumsadat
Submission hash (on-chain): 0x01084ca89022df2e567180e61d19471e12a796e4ee32eeda9c6cd4ed1cdac698
Severity: low

Description:
Description

Calling approve() without first calling approve(0) if the current approval is non-zero will revert with some tokens, such as Tether (USDT). While Tether is known to do this, it applies to other tokens as well, which are trying to protect against this attack vector. safeApprove() itself also implements this protection.
Always reset the approval to zero before changing it to a new value (SafeERC20.forceApprove() does this for you), or use safeIncreaseAllowance()/safeDecreaseAllowance()

file: /contracts/mocks/PoolsManagerMock.sol

64        _asset.approve(address(_target), _amount);

69        _asset.approve(address(_target), _amount * 2);

https://github.com/hats-finance/hats-contracts/blob/0d6ebbde912bc272d9b310140d434ee2aacd36d3/contracts/mocks/PoolsManagerMock.sol#L64

file: /contracts/HATArbitrator.sol

166        _vault.approveClaim(_claimId, 0, address(0));

https://github.com/hats-finance/hats-contracts/blob/0d6ebbde912bc272d9b310140d434ee2aacd36d3/contracts/HATArbitrator.sol#L166

file: /contracts/HATClaimsManager.sol

299        _asset.safeApprove(address(_registry), claimBounty.hackerHatVested + claimBounty.governanceHat);

308        _asset.safeApprove(address(_registry), 0);

https://github.com/hats-finance/hats-contracts/blob/0d6ebbde912bc272d9b310140d434ee2aacd36d3/contracts/HATClaimsManager.sol#L299