native currency fixes

src/PartyPool.sol

@@ -37,6 +37,8 @@ contract PartyPool is PartyPoolBase, ERC20External, IPartyPool {
     using LMSRStabilized for LMSRStabilized.State;
     using SafeERC20 for IERC20;
 
+    receive() external payable {}
+
     function wrapperToken() external view returns (IWETH9) { return WRAPPER_TOKEN; }
 
     /// @notice Liquidity parameter κ (Q64.64) used by the LMSR kernel: b = κ * S(q)