improve

package.json

 {
   "name": "koishi-nestjs",
-  "version": "1.0.16",
+  "version": "1.0.18",
   "description": "Koishi.js as Nest.js Module",
   "main": "dist/index.js",
   "typings": "dist/index.d.ts",

src/koishi-logger.service.ts

-import {
-  ConsoleLogger,
-  Inject,
-  Injectable,
-  OnModuleInit,
-} from '@nestjs/common';
+import { ConsoleLogger, Inject, Injectable } from '@nestjs/common';
 import { Logger } from 'koishi';
 import { KOISHI_MODULE_OPTIONS } from './koishi.constants';
 import { KoishiModuleOptions } from './koishi.interfaces';
@@ -17,29 +12,31 @@ export class KoishiLoggerService extends ConsoleLogger {
     Logger.targets = [
       {
         colors: 3,
-        print(text: string) {
-          const header = text.slice(0, 4);
-          const body = text.slice(4);
-          switch (header) {
-            case '[S] ':
-            case '[I] ':
-              _this.log(body);
-              break;
-            case '[W] ':
-              _this.warn(body);
-              break;
-            case '[E] ':
-              _this.error(body);
-              break;
-            case '[D] ':
-              _this.debug(body);
-              break;
-            default:
-              _this.log(text);
-              break;
-          }
-        },
+        print: (text: string) => this.printKoishiLog(text),
       },
     ];
   }
+
+  private printKoishiLog(text: string) {
+    const header = text.slice(0, 4);
+    const body = text.slice(4);
+    switch (header) {
+      case '[S] ':
+      case '[I] ':
+        this.log(body);
+        break;
+      case '[W] ':
+        this.warn(body);
+        break;
+      case '[E] ':
+        this.error(body);
+        break;
+      case '[D] ':
+        this.debug(body);
+        break;
+      default:
+        this.log(text);
+        break;
+    }
+  }
 }

src/koishi.service.ts

-import { App, Logger } from 'koishi';
+import { App } from 'koishi';
 import {
   ConsoleLogger,
   Inject,