Fix panic in EthGetCode

node/impl/full/eth.go

@@ -441,6 +441,11 @@ func (a *EthModule) EthGetCode(ctx context.Context, ethAddr ethtypes.EthAddress,
 		return nil, xerrors.Errorf("cannot parse block param: %s", blkParam)
 	}
 
+	// StateManager.Call will panic if there is no parent
+	if ts.Height() == 0 {
+		return nil, xerrors.Errorf("block param must not specify genesis block")
+	}
+
 	// Try calling until we find a height with no migration.
 	var res *api.InvocResult
 	for {
@@ -838,7 +843,6 @@ func (a *EthModule) EthCall(ctx context.Context, tx ethtypes.EthCall, blkParam s
 	if msg.To == builtintypes.EthereumAddressManagerActorAddr {
 		// As far as I can tell, the Eth API always returns empty on contract deployment
 		return ethtypes.EthBytes{}, nil
-
 	} else if len(invokeResult.MsgRct.Return) > 0 {
 		return cbg.ReadByteArray(bytes.NewReader(invokeResult.MsgRct.Return), uint64(len(invokeResult.MsgRct.Return)))
 	}