safeApprove() reverts if called a second time without fist calling safeApprove(0)
There is 1 instance of this issue:
https://github.com/code-423n4/2022-05-aura/blob/4989a2077546a5394e3650bf3c224669a0f7e690/contracts/CrvDepositorWrapper.sol#L51-L54
