Emissions sent to vault with null epoch will be lost forever

Summary

When the emissions of the vault are set for a specific epoch they are immediately sent to the contract. When an epoch is null it never reclaims the emissions causing them to be lost.

Vulnerability Detail

https://github.com/sherlock-audit/2023-03-Y2K/blob/main/Earthquake/src/v2/Carousel/CarouselFactory.sol#L132-L153

function createEpochWithEmissions(
    uint256 _marketId,
    uint40 _epochBegin,
    uint40 _epochEnd,
    uint16 _withdrawalFee,
    uint256 _permiumEmissions,
    uint256 _collatEmissions
) public returns (uint256 epochId, address[2] memory vaults) {
    // no need for onlyOwner modifier as createEpoch already has modifier
    (epochId, vaults) = createEpoch(
        _marketId,
        _epochBegin,
        _epochEnd,
        _withdrawalFee
    );

    emissionsToken.safeTransferFrom(treasury, vaults[0], _permiumEmissions);
    ICarousel(vaults[0]).setEmissions(epochId, _permiumEmissions);

    emissionsToken.safeTransferFrom(treasury, vaults[1], _collatEmissions);
    ICarousel(vaults[1]).setEmissions(epochId, _collatEmissions);
}

Here we see the tokens are taken when emissions are created. If there is a null epoch there is no on not claim the tokens so they are lost forever because they aren't transferred back during setting of the null epoch

Impact

Emissions are lost when there is a null epoch

Code Snippet

CarouselFactory.sol#L132-L153

Tool used

Manual Review

Recommendation

Reclaim emissions on null epoch

Duplicate of #122

sherlock-audit / 2023-03-Y2K-judging

0x52 - Emissions sent to vault with null epoch will be lost forever #510