handle ZMQError, which happens if no connections are set up

[engelju]

I wanted to check out the app without setting up all the connections. Prior to this fix, the following error occured:

Traceback (most recent call last):
  File "/usr/local/Cellar/python3/3.5.1/Frameworks/Python.framework/Versions/3.5/lib/python3.5/runpy.py", line 170, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/local/Cellar/python3/3.5.1/Frameworks/Python.framework/Versions/3.5/lib/python3.5/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "chatimusmaximus/__main__.py", line 81, in <module>
    main()
  File "chatimusmaximus/__main__.py", line 51, in main
    messager.subscribe_to_publishers(settings_data['sockets_to_connect_to'])
  File "/Users/julieengel/tmp/CHATIMUSMAXIMUS/chatimusmaximus/messaging.py", line 22, in subscribe_to_publishers
    self.sub_socket.connect(address)
  File "zmq/backend/cython/socket.pyx", line 514, in zmq.backend.cython.socket.Socket.connect (zmq/backend/cython/socket.c:5376)
zmq.error.ZMQError: Invalid argument

After this fix is applied, the GUI will show/open normally, of course without any connections active.

[engelju]

perhaps issue #30 could be related.

[benhoff]

Nice fix! Sorry it didn't work out of the box for you, but I'll get this wrapped in and merged probably later tonight

[engelju]

No problem, glad I could help! I am a big fan of your streams, they're really helpful.

[benhoff]

Thanks again for the patch!