ChakraSettlementHandler::receive_cross_chain_msg contains 2 identical checks regarding the payload type and one of them is redundant:
ChakraSettlementHandler.sol
As we can see the first require isValidPayloadType is redundant because the if check below does the same. As a result when the payload type is not ERC20 we will revert, without even entering the check in the if statement. 
Remove the require statement and add else statement, so when the other payload types are supported it will be easier to upgrade the contracts:
