Check for type differences with is_type for None safety.

Author: GraylinKim

sc2reader/events/tracker.py

@@ -411,7 +411,7 @@ def load_context(self, replay):
         if self.unit_id in replay.objects:
             # This can happen because game events are done first
             self.unit = replay.objects[self.unit_id]
-            if self.unit._type_class.str_id != self.unit_type_name:
+            if self.unit.is_type(self.unit_type_name):
                 print "CONFLICT {} <-_-> {}".format(self.unit._type_class.str_id, self.unit_type_name)
         else:
             # TODO: How to tell if something is hallucination?