     @MINIFY_THRESHOLD = 3
 
   componentDidMount: =>
+    @_mounted = true
+
     window.addEventListener("resize", @_onResize)
     @_unsubscribers = []
     @_unsubscribers.push MessageStore.listen @_onChange

    lastHeight = -1
    stableCount = 0
    scrollIfSettled = =>
      messageWrapHeight = messageWrap.getBoundingClientRect().height
      if messageWrapHeight isnt lastHeight
        lastHeight = messageWrapHeight

      @_prepareContentForDisplay()

  componentWillUnmount: =>
    @_mounted = false
    unsubscribe() for unsubscribe in @_unsubscribers
    @command_unsubscriber.dispose()

