PyQT/play.py KeyError when update_buffer was called

I got the following `KeyError`:
```
File "PyQt/play.py", line 274, in draw
    self.update_buffer(m[1], m[2])
  File "PyQt/play.py", line 175, in update_buffer
    ix = self.buffer_order[sender]
KeyError: '127.0.1.1,47525'
Violación de segmento
```