Check if transport has been set when closing

The transport doesn't get set as soon as the response handler is
created, it's set some time later. If the handler is closed immediately
it can be before the transport has been set, and in that case we don't
need it.

Fixes #46

Author: tonyroberts

custom_components/wundasmart/session.py

@@ -34,7 +34,8 @@ def __init__(self, *args, **kwargs):
         self.__closed_transport = None
 
     def close(self):
-        self.__closed_transport = weakref.ref(self.transport)
+        if self.transport is not None:
+            self.__closed_transport = weakref.ref(self.transport)
         super().close()
 
     def connection_lost(self, exc):