chore: make static_check happy

apps/emqx_gateway_coap/src/emqx_coap_pubsub_handler.erl

@@ -110,10 +110,7 @@ type_to_qos(coap, #coap_message{type = Type}) ->
     end.
 
 get_publish_opts(Msg) ->
-    case emqx_coap_message:extract_uri_query(Msg) of
-        undefined ->
-            #{};
-        Qs ->
+    Qs = emqx_coap_message:extract_uri_query(Msg),
     maps:fold(
         fun
             (<<"retain">>, V, Acc) ->
@@ -130,8 +127,7 @@ get_publish_opts(Msg) ->
         end,
         #{},
         Qs
-            )
-    end.
+    ).
 
 get_publish_qos(Msg, PublishOpts) ->
     case PublishOpts of