Fix trace pending txns

rpc/trace.go

@@ -141,24 +141,37 @@ func (h *Handler) traceTransaction(ctx context.Context, hash *felt.Felt) (*vm.Tr
 	httpHeader := http.Header{}
 	httpHeader.Set(ExecutionStepsHeader, "0")
 
+	var block *core.Block
 	if err != nil {
-		return nil, httpHeader, ErrTxnHashNotFound
+		pendingB := h.syncReader.PendingBlock()
+		if pendingB == nil {
+			return nil, httpHeader, ErrTxnHashNotFound
+		}
+
+		txIndex := slices.IndexFunc(pendingB.Transactions, func(tx core.Transaction) bool {
+			return tx.Hash().Equal(hash)
+		})
+		if txIndex == -1 {
+			return nil, httpHeader, ErrTxnHashNotFound
+		}
+
+		traceResults, header, traceBlockErr := h.traceBlockTransactions(ctx, pendingB)
+		if traceBlockErr != nil {
+			return nil, header, traceBlockErr
+		}
+		return traceResults[txIndex].TraceRoot, header, nil
 	}
 
-	var block *core.Block
-	isPendingBlock := blockHash == nil
-	if isPendingBlock {
+	if blockHash == nil {
 		var pending *sync.Pending
 		pending, err = h.syncReader.Pending()
 		if err != nil {
-			// for traceTransaction handlers there is no block not found error
 			return nil, httpHeader, ErrTxnHashNotFound
 		}
 		block = pending.Block
 	} else {
 		block, err = h.bcReader.BlockByHash(blockHash)
 		if err != nil {
-			// for traceTransaction handlers there is no block not found error
 			return nil, httpHeader, ErrTxnHashNotFound
 		}
 	}