Ensure stanzas other than Presence, Message, and IQ don't crash the client.

[scrogson]

When a client is signed in with a given resource and you attempt to connect another instance with the same resource, you end up with a resource conflict. You will receive the following error stanza:

<stream:error>
  <conflict xmlns='urn:ietf:params:xml:ns:xmpp-streams'></conflict>
  <text xml:lang='en' xmlns='urn:ietf:params:xml:ns:xmpp-streams'>
    Replaced by new connection
  </text>
</stream:error>

This will crash the client.

Error in process <0.9905.0> on node 'hedwig@127.0.0.1' with exit value: {badarg,[{'Elixir.Hedwig.Client',handle_stanza,2,[{file,
"lib/hedwig/client.ex"},{line,77}]},{'Elixir.Hedwig.Conn',await,1,[{file,"lib/hedwig/conn.ex"},{line,137}]}]}

Should probably just ignore when a record gets passed to handle_stanza/2:

def handle_stanza(_pid, stanza) when Record.is_record(stanza) do
  Logger.warn fn -> "Unhandled stanza: #{inspect stanza}" end
end

[jamesjahraus]

I also have a similar error that I think is related to this issue:
14:57:29.955 [error] Process #PID<0.157.0> raised an exception
** (BadMapError) expected a map, got: {:xmlstreamend, "stream:stream"}
(hedwig) lib/hedwig/client.ex:78: Hedwig.Client.handle_stanza/2
(hedwig) lib/hedwig/conn.ex:133: Hedwig.Conn.await/1

I tried to modify handle_stanza/2 as you suggested, but I did not correct the problem. I am not too sure how to fix this, a case maybe?

My goal is to get many (1000 +)processes responding to a handler I created, currently I can only get 5, supervisor can not seem to start them fast enough. Looking at the observer the pids are changing very fast, so I assume each client is continually crashing.

Do you have any suggestions to fix handle_stanza/2.

Thanks