Fixed issue #1841: Taskbar item race condition causes JS exception.

app/assets/javascripts/app/lib/spine/spine.coffee

@@ -417,6 +417,15 @@ class Model extends Module
     # ID change, need to do some shifting
     if atts.id and @id isnt atts.id
       @changeID(atts.id)
+
+    # temporary debugging of a possible race condition
+    if !@constructor.irecords[@id]
+      model     = @constructor.className
+      atts_json = JSON.stringify(atts)
+      console.notice "Can't refresh not exisint %s instance with ID %s and attributes %s. Possible race condition?", model, @id, atts_json
+      # prevent exception
+      return
+
     # go to the source and load attributes
     @constructor.irecords[@id].load(atts)
     @trigger('refresh', this)