server: fix some bugs lol

server.py

@@ -109,9 +109,11 @@ class Session(object):
         print(self.connection_id, "going away")
         if self.sender is not None:
             self.sender.end()
+        if self.pc is not None:
             await self.pc.close()
         init_buffers()
         write_ob_status(False)
+        if self.websocket is not None:
             await self.websocket.send(json.dumps({"kind": "REPLACED"}))
 
     def create_peerconnection(self):
@@ -166,7 +168,7 @@ class Session(object):
             answer = await self.pc.createAnswer()
             await self.pc.setLocalDescription(answer)
 
-            await websocket.send(
+            await self.websocket.send(
                 json.dumps(
                     {
                         "kind": "ANSWER",