UpdateLocation being sent by client/server even if no session is joined

[saidelike]

This error seems related to #36

What happens is idarling connects to the server when IDA is started but not session was ever joined because we never uploaded it:

[idarling][DEBUG] Loaded netnode: group=None, project=None, database=None, tick=0
...

Then it seems the client is sending UpdateLocation even though we are not joined in a session.

And also we receive UpdateLocation messages that we handle but obviously they are useless and an exception occurs:

[idarling][DEBUG] Received packet: UpdateLocation(type=command, command_type=update_location, name=cedric, ea=7516290727, color=16775936)[idarling][DEBUG] get_user(cedric): {}
Traceback (most recent call last):
  File "C:/Users/User/AppData/Roaming/Hex-Rays/IDA Pro/plugins\idarling\shared\sockets.py", line 302, in event
    self._dispatch()
  File "C:/Users/User/AppData/Roaming/Hex-Rays/IDA Pro/plugins\idarling\shared\sockets.py", line 320, in _dispatch
    elif not self.recv_packet(packet):
  File "C:/Users/User/AppData/Roaming/Hex-Rays/IDA Pro/plugins\idarling\network\client.py", line 80, in recv_packet
    self._handlers[packet.__class__](packet)
  File "C:/Users/User/AppData/Roaming/Hex-Rays/IDA Pro/plugins\idarling\network\client.py", line 169, in _handle_update_location
    user = self._plugin.core.get_user(packet.name)
  File "C:/Users/User/AppData/Roaming/Hex-Rays/IDA Pro/plugins\idarling\core\core.py", line 132, in get_user
    self._plugin.logger.debug("get_user(%s): %s" % (name, self._users)) # tmp
KeyError: 'cedric'