check if dataSet postition is valid

workaround for #1187

True problem is probably dataSet getting updated too early

app/src/main/java/code/name/monkey/retromusic/adapter/SongFileAdapter.kt

@@ -142,7 +142,7 @@ class SongFileAdapter(
     }
 
     override fun getPopupText(position: Int): String {
-        return getSectionName(position)
+        return if (position >= dataSet.lastIndex) "" else getSectionName(position)
     }
 
     private fun getSectionName(position: Int): String {