dialyzer: Fix incorrect case pattern
dialyzer: Fix incorrect case pattern

apps/vmq_server/src/vmq_websocket.erl
  36: The pattern {'undefined', Req2} can never match the type {'error','badarg'} | {'ok',_,cowboy_req:req()} | {'undefined',binary(),cowboy_req:req()}

erlio/vernemq,erlio/vernemq,erlio/vernemq,erlio/vernemq