chore: fix dialyzer warnings

apps/emqx_gateway/src/emqx_gateway_utils.erl

@@ -144,7 +144,7 @@ start_listeners([L | Ls], GwName, Ctx, ModCfg, Acc) ->
                      Ctx :: emqx_gateway_ctx:context(),
                      Listener :: tuple(),
                      ModCfg :: map())
-    -> {ok, pid()}
+    -> {ok, {ListenerId :: atom(), esockd:listen_on(), pid()}}
      | {error, term()}.
 start_listener(GwName, Ctx,
                {Type, LisName, ListenOn, SocketOpts, Cfg}, ModCfg) ->

apps/emqx_gateway/src/lwm2m/emqx_lwm2m_impl.erl

@@ -62,7 +62,7 @@ on_gateway_load(_Gateway = #{ name := GwName,
                 {ok, ListenerPids} ->
                     {ok, ListenerPids, #{ctx => Ctx, registry => RegPid}};
                 {error, {Reason, Listener}} ->
-                    emqx_lwm2m_xml_object_db:stop(),
+                    _ = emqx_lwm2m_xml_object_db:stop(),
                     throw({badconf, #{ key => listeners
                                      , vallue => Listener
                                      , reason => Reason