feat: 优化代码

app/src/main/java/io/legado/app/service/help/ReadBook.kt

@@ -33,7 +33,7 @@ object ReadBook {
     var curTextChapter: TextChapter? = null
     var nextTextChapter: TextChapter? = null
     var webBook: WebBook? = null
-    private var msg: String? = null
+    var msg: String? = null
     private val loadingChapters = arrayListOf<Int>()
 
     fun resetData(book: Book, noSource: (name: String, author: String) -> Unit) {

app/src/main/java/io/legado/app/ui/book/read/ReadBookActivity.kt

@@ -682,6 +682,7 @@ class ReadBookActivity : VMBaseActivity<ReadBookViewModel>(R.layout.activity_boo
         mHandler.removeCallbacks(keepScreenRunnable)
         textActionMenu?.dismiss()
         page_view.onDestroy()
+        ReadBook.msg = null
         if (!BuildConfig.DEBUG) {
             SyncBookProgress.uploadBookProgress()
             Backup.autoBack(this)