Avoid crash in DeleteLibraryMangaDialog

No clue why it ever gets a -1 index though.

(cherry picked from commit b12c7cf963)

app/src/main/java/eu/kanade/presentation/components/DeleteLibraryMangaDialog.kt

@@ -64,10 +64,12 @@ fun DeleteLibraryMangaDialog(
                 list.forEach { state ->
                     val onCheck = {
                         val index = list.indexOf(state)
+                        if (index != -1) {
                             val mutableList = list.toMutableList()
                             mutableList[index] = state.next() as CheckboxState.State<Int>
                             list = mutableList.toList()
                         }
+                    }
 
                     Row(
                         modifier = Modifier