text: Title: "NoneType object is not callable" on stopping P2P
  Body: I have very simple inference testing script. No threading or any advanced stuff. Basically "hello world" inference on Petals. Everything is going well, but when the script is exiting, I always get this error:
  
  ```
  Exception ignored in: <function P2P.__del__ at 0x7f4ac1feed40>
  Traceback (most recent call last):
    File "/home/dev/.local/lib/python3.10/site-packages/hivemind/p2p/p2p_daemon.py", line 632, in __del__
    File "/home/dev/.local/lib/python3.10/site-packages/hivemind/p2p/p2p_daemon.py", line 659, in _terminate
    File "/home/dev/.local/lib/python3.10/site-packages/multiaddr/multiaddr.py", line 254, in value_for_protocol
  TypeError: 'NoneType' object is not callable
  ```
  It is rather cosmetic issue, but something is not OK there.