Submitted by WatchPug
CTokenInterfaces.sol#L345
mint() for native cToken (CEther) will return nothing, while the current CEthInterface interface defines the returns as (uint256).
In the current implementation, the interface for CToken is used for both CEther and CErc20.
As a result, the transaction will revert with the error: function returned an unexpected amount of data when topUp() with the native token (ETH).
CompoundHandler.sol#L57-L70
Ref:
chase-manning (Backd) confirmed
