优化

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

@@ -168,20 +168,24 @@ class ReadBookViewModel(application: Application) : BaseViewModel(application) {
         book: Book,
         alertSync: ((progress: BookProgress) -> Unit)? = null
     ) {
-        if (AppWebDav.syncBookProgress)
         execute {
+            if (AppWebDav.syncBookProgress) {
                 AppWebDav.getBookProgress(book)
-            }.onSuccess {
+                    ?: throw NoStackTraceException("没有进度")
-                it?.let { progress ->
+            } else {
+                throw NoStackTraceException("进度同步未启用")
+            }
+        }.onSuccess { progress ->
             if (progress.durChapterIndex < book.durChapterIndex ||
-                        (progress.durChapterIndex == book.durChapterIndex && progress.durChapterPos < book.durChapterPos)
+                (progress.durChapterIndex == book.durChapterIndex
+                    && progress.durChapterPos < book.durChapterPos)
             ) {
                 alertSync?.invoke(progress)
             } else {
                 ReadBook.setProgress(progress)
             }
         }
-            }
+
     }
 
     /**