Merge pull request #2051 from dev-ritik/issue_2041

[FIX] Fixes app crashes when channel Details button is clicked while scrolling

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

@@ -259,7 +259,7 @@ class ChatRoomFragment : Fragment(), ChatRoomView, EmojiKeyboardListener, EmojiR
                 button_fab.hide()
                 newMessageCount = 0
             } else {
-                if (dy < 0 && !button_fab.isVisible) {
+                if (dy < 0 && isAdded && !button_fab.isVisible) {
                     button_fab.show()
                     if (newMessageCount != 0) text_count.isVisible = true
                 }