Submitted by gpersoon
The initializeYieldSourcePrizePool function of YieldSourcePrizePool.sol has a check to make sure _yieldSource !=0. However, the initialize function  of the comparable StakePrizePool.sol doesnt do this check.
Although unlikely this will introduce problems, it is more consistent to check for 0.
YieldSourcePrizePool.sol L24
StakePrizePool.sol L20
Recommend adding something like the following in the initialize function of StakePrizePool.sol:
