fix eth_callBundle by allowing nil baseFee in tx serialize (#2674)

core/types/dynamic_fee_tx.go

@@ -469,9 +469,11 @@ func (tx DynamicFeeTransaction) AsMessage(s Signer, baseFee *big.Int) (Message,
 		accessList: tx.AccessList,
 		checkNonce: true,
 	}
-	overflow := msg.gasPrice.SetFromBig(baseFee)
-	if overflow {
-		return msg, fmt.Errorf("gasPrice higher than 2^256-1")
+	if baseFee != nil {
+		overflow := msg.gasPrice.SetFromBig(baseFee)
+		if overflow {
+			return msg, fmt.Errorf("gasPrice higher than 2^256-1")
+		}
 	}
 	msg.gasPrice.Add(&msg.gasPrice, tx.Tip)
 	if msg.gasPrice.Gt(tx.FeeCap) {