Fix NPE on ChatRoomFragment

app/src/main/java/chat/rocket/android/chatroom/ui/ChatRoomFragment.kt

@@ -135,6 +135,10 @@ class ChatRoomFragment : Fragment(), ChatRoomView, EmojiKeyboardListener, EmojiR
     }
 
     override fun onDestroyView() {
+        recycler_view.removeOnScrollListener(endlessRecyclerViewScrollListener)
+        recycler_view.removeOnScrollListener(onScrollListener)
+        recycler_view.removeOnLayoutChangeListener(layoutChangeListener)
+
         presenter.unsubscribeMessages(chatRoomId)
         handler.removeCallbacksAndMessages(null)
         unsubscribeTextMessage()
@@ -208,16 +212,25 @@ class ChatRoomFragment : Fragment(), ChatRoomView, EmojiKeyboardListener, EmojiR
                 recycler_view.layoutManager = linearLayoutManager
                 recycler_view.itemAnimator = DefaultItemAnimator()
                 if (dataSet.size >= 30) {
-                    recycler_view.addOnScrollListener(object : EndlessRecyclerViewScrollListener(linearLayoutManager) {
-                        override fun onLoadMore(page: Int, totalItemsCount: Int, recyclerView: RecyclerView?) {
-                            presenter.loadMessages(chatRoomId, chatRoomType, page * 30L)
+                    recycler_view.addOnScrollListener(endlessRecyclerViewScrollListener)
+                }
+                recycler_view.addOnLayoutChangeListener(layoutChangeListener)
+                recycler_view.addOnScrollListener(onScrollListener)
+            }
+
+            val oldMessagesCount = adapter.itemCount
+            adapter.appendData(dataSet)
+            if (oldMessagesCount == 0 && dataSet.isNotEmpty()) {
+                recycler_view.scrollToPosition(0)
+                verticalScrollOffset.set(0)
+            }
+            presenter.loadActiveMembers(chatRoomId, chatRoomType, filterSelfOut = true)
         }
-                    })
     }
 
-                recycler_view.addOnLayoutChangeListener { _, _, _, _, bottom, _, _, _, oldBottom ->
+    private val layoutChangeListener = View.OnLayoutChangeListener { _, _, _, _, bottom, _, _, _, oldBottom ->
         val y = oldBottom - bottom
-                    if (y.absoluteValue > 0) {
+        if (y.absoluteValue > 0 && isAdded) {
             // if y is positive the keyboard is up else it's down
             recycler_view.post {
                 if (y > 0 || verticalScrollOffset.get().absoluteValue >= y.absoluteValue) {
@@ -229,7 +242,13 @@ class ChatRoomFragment : Fragment(), ChatRoomView, EmojiKeyboardListener, EmojiR
         }
     }
 
-                recycler_view.addOnScrollListener(object : RecyclerView.OnScrollListener() {
+    private val endlessRecyclerViewScrollListener = object : EndlessRecyclerViewScrollListener(recycler_view.layoutManager as LinearLayoutManager) {
+        override fun onLoadMore(page: Int, totalItemsCount: Int, recyclerView: RecyclerView?) {
+            presenter.loadMessages(chatRoomId, chatRoomType, page * 30L)
+        }
+    }
+
+    private val onScrollListener = object : RecyclerView.OnScrollListener() {
         var state = AtomicInteger(RecyclerView.SCROLL_STATE_IDLE)
 
         override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
@@ -254,17 +273,6 @@ class ChatRoomFragment : Fragment(), ChatRoomView, EmojiKeyboardListener, EmojiR
                 verticalScrollOffset.getAndAdd(dy)
             }
         }
-                })
-            }
-
-            val oldMessagesCount = adapter.itemCount
-            adapter.appendData(dataSet)
-            if (oldMessagesCount == 0 && dataSet.isNotEmpty()) {
-                recycler_view.scrollToPosition(0)
-                verticalScrollOffset.set(0)
-            }
-            presenter.loadActiveMembers(chatRoomId, chatRoomType, filterSelfOut = true)
-        }
     }
 
     override fun sendMessage(text: String) {