diff --git a/backend/block.go b/backend/block.go
index f4e1ac4..960afa2 100644
--- a/backend/block.go
+++ b/backend/block.go
@@ -31,6 +31,10 @@ func (fs *ChainDB) Blocks() []*types.Block {
 	return fs.blocks
 }
 
+func (fs *ChainDB) Txs() uint64 {
+	return fs.txs.Load()
+}
+
 func (fs *ChainDB) GetBlockByNumber(blockNum uint64) *types.Block {
 	var block types.Block
 
diff --git a/backend/chaindb.go b/backend/chaindb.go
index dc2b4c6..0cfe0ce 100644
--- a/backend/chaindb.go
+++ b/backend/chaindb.go
@@ -145,10 +145,6 @@ func (fs *ChainDB) Init() (err error) {
 	return
 }
 
-func (fs *ChainDB) Txs() uint64 {
-	return fs.txs.Load()
-}
-
 func (fs *ChainDB) Reset() error {
 	fs.blocks = nil
 	fs.checkPoint.Store(0)
@@ -166,10 +162,6 @@ func (fs *ChainDB) Close() error {
 	return fs.Flush()
 }
 
-var (
-	ErrReadDataFromBoltDB = errors.New("bolt DB Read Error")
-)
-
 func (fs *ChainDB) Version() string {
 	return fs.version
 }
diff --git a/backend/errors.go b/backend/errors.go
new file mode 100644
index 0000000..bf83435
--- /dev/null
+++ b/backend/errors.go
@@ -0,0 +1,25 @@
+// Copyright 2023 The CortexTheseus Authors
+// This file is part of the CortexTheseus library.
+//
+// The CortexTheseus library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The CortexTheseus library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the CortexTheseus library. If not, see <http://www.gnu.org/licenses/>.
+
+package backend
+
+import (
+	"errors"
+)
+
+var (
+	ErrReadDataFromBoltDB = errors.New("bolt DB Read Error")
+)