Submitted by WatchPug, also found by kenzo, and certora
For unstarted promotions, cancelPromotion() will revert at block.timestamp - _promotion.startTimestamp in _getCurrentEpochId().
Call stack: cancelPromotion() -> _getRemainingRewards() -> _getCurrentEpochId().
https://github.com/pooltogether/v4-periphery/blob/0e94c54774a6fce29daf9cb23353208f80de63eb/contracts/TwabRewards.sol#L331-L336
https://github.com/pooltogether/v4-periphery/blob/0e94c54774a6fce29daf9cb23353208f80de63eb/contracts/TwabRewards.sol#L276-L279
Consider checking if _promotion.startTimestamp > block.timestamp and refund _promotion.tokensPerEpoch * _promotion.numberOfEpochs in cancelPromotion().
PierrickGT (PoolTogether) confirmed 
