eth/tracers: return proper error from debug_TraceTransaction when tx not found (#26211)

Currently calling `debug_TraceTransaction` with a transaction hash that doesn't exist returns a confusing error: `genesis is not traceable`. This PR changes the behaviour to instead return an error message saying `transaction not found`
Co-authored-by: Martin Holst Swende <martin@swende.se>
Co-authored-by: Sina Mahmoodi <itz.s1na@gmail.com>

eth/tracers/api.go

@@ -68,6 +68,8 @@ const (
 	maximumPendingTraceStates = 128
 )
 
+var errTxNotFound = errors.New("transaction not found")
+
 // StateReleaseFunc is used to deallocate resources held by constructing a
 // historical state for tracing purposes.
 type StateReleaseFunc func()
@@ -801,10 +803,14 @@ func containsTx(block *types.Block, hash common.Hash) bool {
 // TraceTransaction returns the structured logs created during the execution of EVM
 // and returns them as a JSON object.
 func (api *API) TraceTransaction(ctx context.Context, hash common.Hash, config *TraceConfig) (interface{}, error) {
-	_, blockHash, blockNumber, index, err := api.backend.GetTransaction(ctx, hash)
+	tx, blockHash, blockNumber, index, err := api.backend.GetTransaction(ctx, hash)
 	if err != nil {
 		return nil, err
 	}
+	// Only mined txes are supported
+	if tx == nil {
+		return nil, errTxNotFound
+	}
 	// It shouldn't happen in practice.
 	if blockNumber == 0 {
 		return nil, errors.New("genesis is not traceable")

eth/tracers/api_test.go

@@ -48,9 +48,8 @@ import (
 )
 
 var (
-	errStateNotFound       = errors.New("state not found")
-	errBlockNotFound       = errors.New("block not found")
-	errTransactionNotFound = errors.New("transaction not found")
+	errStateNotFound = errors.New("state not found")
+	errBlockNotFound = errors.New("block not found")
 )
 
 type testBackend struct {
@@ -117,9 +116,6 @@ func (b *testBackend) BlockByNumber(ctx context.Context, number rpc.BlockNumber)
 
 func (b *testBackend) GetTransaction(ctx context.Context, txHash common.Hash) (*types.Transaction, common.Hash, uint64, uint64, error) {
 	tx, hash, blockNumber, index := rawdb.ReadTransaction(b.chaindb, txHash)
-	if tx == nil {
-		return nil, common.Hash{}, 0, 0, errTransactionNotFound
-	}
 	return tx, hash, blockNumber, index, nil
 }
 
@@ -365,6 +361,12 @@ func TestTraceTransaction(t *testing.T) {
 	}) {
 		t.Error("Transaction tracing result is different")
 	}
+
+	// Test non-existent transaction
+	_, err = api.TraceTransaction(context.Background(), common.Hash{42}, nil)
+	if !errors.Is(err, errTxNotFound) {
+		t.Fatalf("want %v, have %v", errTxNotFound, err)
+	}
 }
 
 func TestTraceBlock(t *testing.T) {