优化

app/src/main/java/io/legado/app/model/ReadBook.kt

@@ -196,7 +196,7 @@ object ReadBook : CoroutineScope by MainScope() {
         toLast: Boolean = true
     ): Boolean {
         if (durChapterIndex > 0) {
-            durChapterPos = if (toLast) prevTextChapter?.lastReadLength ?: 0 else 0
+            durChapterPos = if (toLast) prevTextChapter?.lastReadLength ?: Int.MAX_VALUE else 0
             durChapterIndex--
             nextTextChapter = curTextChapter
             curTextChapter = prevTextChapter