优化

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

@@ -147,13 +147,11 @@ class ReadBookViewModel(application: Application) : BaseViewModel(application) {
             }
         } else {
             ReadBook.bookSource?.let {
-                viewModelScope.launch {
+                viewModelScope.launch(IO) {
-                    withContext(IO) {
                     val preUpdateJs = it.ruleToc?.preUpdateJs
                     if (!preUpdateJs.isNullOrBlank()) {
                         AnalyzeRule(book, it).evalJS(preUpdateJs)
                     }
-                    }
                     WebBook.getChapterList(viewModelScope, it, book)
                         .onSuccess(IO) { cList ->
                             appDb.bookChapterDao.insert(*cList.toTypedArray())