Fixing D&D sorting sometimes giving a blank library

app/src/main/java/eu/kanade/tachiyomi/ui/library/LibraryPresenter.kt

@@ -275,6 +275,7 @@ class LibraryPresenter(
                                 val index1 = order.indexOf(i1.manga.id!!)
                                 val index2 = order.indexOf(i2.manga.id!!)
                                 when {
+                                    index1 == index2 -> 0
                                     index1 == -1 -> -1
                                     index2 == -1 -> 1
                                     else -> index1.compareTo(index2)

app/src/main/java/eu/kanade/tachiyomi/ui/main/MainActivity.kt

@@ -392,7 +392,7 @@ open class MainActivity : BaseActivity() {
             drawer.closeDrawers()
         } else if (backstackSize == 1 && router.getControllerWithTag("$startScreenId") == null) {
             setSelectedDrawerItem(startScreenId)
-        } else if (backstackSize == 1 || !router.handleBack()) {
+        } else if (!router.handleBack()) {
             unlocked = false
             super.onBackPressed()
         }