BRG4-15: error out early if nil pubkey provided when creating PoL tx

core/types/tx_pol.go

@@ -18,6 +18,7 @@ package types
 
 import (
 	"bytes"
+	"errors"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/accounts/abi"
@@ -145,14 +146,11 @@ var (
 
 // getDistributeForData returns the tx data for the `distributeFor(bytes pubkey)` method.
 func getDistributeForData(pubkey *common.Pubkey) ([]byte, error) {
-	var pubkeyBytes []byte
 	if pubkey == nil {
-		pubkeyBytes = common.Pubkey{}.Bytes()
-	} else {
-		pubkeyBytes = pubkey.Bytes()
+		return nil, errors.New("pubkey cannot be nil for PoL transaction")
 	}
 
-	arguments, err := distributeForMethod.Inputs.Pack(pubkeyBytes)
+	arguments, err := distributeForMethod.Inputs.Pack(pubkey.Bytes())
 	if err != nil {
 		return nil, err
 	}

core/types/tx_pol_test.go

@@ -65,6 +65,27 @@ func TestNewPoLTx_DataPacking(t *testing.T) {
 	}
 }
 
+// TestNewPoLTx_NilPubkey verifies that NewPoLTx returns an error when pubkey is nil.
+func TestNewPoLTx_NilPubkey(t *testing.T) {
+	chainID := big.NewInt(1)
+	distributor := common.HexToAddress("0x000000000000000000000000000000000000dEaD")
+	blockNum := big.NewInt(123)
+	baseFee := big.NewInt(1000000000)
+
+	// Call NewPoLTx with nil pubkey
+	tx, err := NewPoLTx(chainID, distributor, blockNum, params.PoLTxGasLimit, baseFee, nil)
+	if err == nil {
+		t.Fatalf("expected error for nil pubkey, but got nil")
+	}
+	if tx != nil {
+		t.Fatalf("expected nil transaction when error occurs, but got %v", tx)
+	}
+	expectedErr := "pubkey cannot be nil for PoL transaction"
+	if err.Error() != expectedErr {
+		t.Fatalf("error message mismatch: have %q, want %q", err.Error(), expectedErr)
+	}
+}
+
 // TestNewPoLTx_NegativeBlockNumber ensures negative block numbers are handled
 // without panicking (uint64 wrap-around is expected).
 func TestNewPoLTx_NegativeBlockNumber(t *testing.T) {