fix: Coverage stack too deep

[0xhiroshi]

A pleasant surprise...while trying to get the contracts to compile for npx hardhat coverage, made some gas improvement as a side effect.

testBuyWithERC20ButMsgSenderIsNotERC20EnabledLooksRareAggregator() (gas: -3 (-0.000%))
testExecuteOrdersLengthMismatch() (gas: -3 (-0.005%))
testExecuteZeroOrders() (gas: -3 (-0.007%))
testExecuteZeroRecipient() (gas: -3 (-0.019%))
testExecuteThroughV0AggregatorTwoOrders() (gas: -774 (-0.020%))
testExecuteZeroOrders() (gas: -3 (-0.020%))
testExecuteThroughV0AggregatorSingleOrder() (gas: -774 (-0.021%))
testBuyFromLooksRareAggregatorTwoNFTsEachMarketplaceNonAtomic() (gas: -10814 (-0.158%))
testBuyFromLooksRareAggregatorTwoNFTsEachMarketplaceAtomic() (gas: -11051 (-0.161%))
testBuyFromLooksRareAggregatorNonAtomic() (gas: -10926 (-0.169%))
testBuyFromLooksRareAggregatorAtomic() (gas: -11004 (-0.170%))
testExecuteReentrancy() (gas: -10683 (-0.186%))
testExecuteThroughAggregatorTwoOrders() (gas: -10261 (-0.216%))
testExecuteThroughAggregatorTwoOrders() (gas: -9495 (-0.223%))
testExecuteThroughAggregatorSingleOrder() (gas: -10255 (-0.224%))
testExecuteZeroOriginator() (gas: -9490 (-0.233%))
testExecuteThroughAggregatorSingleOrder() (gas: -9490 (-0.233%))
testBuyZeroTokenTransfers() (gas: -6008 (-37.317%))
Overall gas change: -111040 (-39.381%)