eth/catalyst: return error if withdrawals are nil post-shanghai (#26691)

Spec: https://github.com/ethereum/execution-apis/blob/main/src/engine/shanghai.md#request

eth/catalyst/api.go

@@ -410,13 +410,20 @@ func (api *ConsensusAPI) getPayload(payloadID engine.PayloadID) (*engine.Executi
 // NewPayloadV1 creates an Eth1 block, inserts it in the chain, and returns the status of the chain.
 func (api *ConsensusAPI) NewPayloadV1(params engine.ExecutableData) (engine.PayloadStatusV1, error) {
 	if params.Withdrawals != nil {
-		return engine.PayloadStatusV1{Status: engine.INVALID}, fmt.Errorf("withdrawals not supported in V1")
+		return engine.PayloadStatusV1{Status: engine.INVALID}, engine.InvalidParams.With(fmt.Errorf("withdrawals not supported in V1"))
 	}
 	return api.newPayload(params)
 }
 
 // NewPayloadV2 creates an Eth1 block, inserts it in the chain, and returns the status of the chain.
 func (api *ConsensusAPI) NewPayloadV2(params engine.ExecutableData) (engine.PayloadStatusV1, error) {
+	if api.eth.BlockChain().Config().IsShanghai(params.Timestamp) {
+		if params.Withdrawals == nil {
+			return engine.PayloadStatusV1{Status: engine.INVALID}, engine.InvalidParams.With(fmt.Errorf("nil withdrawals post-shanghai"))
+		}
+	} else if params.Withdrawals != nil {
+		return engine.PayloadStatusV1{Status: engine.INVALID}, engine.InvalidParams.With(fmt.Errorf("non-nil withdrawals pre-shanghai"))
+	}
 	return api.newPayload(params)
 }