diff --git a/lib/common/segmentit/index.ts b/lib/common/segmentit/index.ts
index cc42363..a9d2647 100644
--- a/lib/common/segmentit/index.ts
+++ b/lib/common/segmentit/index.ts
@@ -96,7 +96,7 @@ export class AC {
 
     while (queue.length > queueIndex) {
       let node = queue[queueIndex++] as TrieNode;
-      let failNode = node && node.parent && node.parent.fail as TrieNode | null;
+      let failNode = node.parent && node.parent.fail as TrieNode | null;
       let key = node.key;
 
       while (failNode && !failNode.children.has(key)) {
diff --git a/lib/common/utils.ts b/lib/common/utils.ts
index cf914c1..8bdddb5 100644
--- a/lib/common/utils.ts
+++ b/lib/common/utils.ts
@@ -1,4 +1,4 @@
-import { DoubleUnicodePrefixReg, DoubleUnicodeSuffixReg, DoubleUnicodeReg } from './constant';
+import { DoubleUnicodeReg } from './constant';
 
 export function getStringLength(string: string) {
   return string.replace(DoubleUnicodeReg, '_').length;
diff --git a/vitest.config.js b/vitest.config.js
index b5bc040..d42b85d 100644
--- a/vitest.config.js
+++ b/vitest.config.js
@@ -1,4 +1,4 @@
-import { configDefaults, defineConfig } from 'vitest/config';
+import { defineConfig } from 'vitest/config';
 import path from 'path';
 
 export default defineConfig({