fix(resource): don't destruct error tuple

Otherwise, `emqx_resource:query` won't correctly deem the resource to
be unhealthy when there's an extra message.

apps/emqx_bridge/src/emqx_bridge_api.erl

@@ -546,7 +546,12 @@ schema("/bridges_probe") ->
                     ?NO_CONTENT;
                 {error, #{kind := validation_error} = Reason} ->
                     ?BAD_REQUEST('TEST_FAILED', map_to_json(Reason));
-                {error, Reason} when not is_tuple(Reason); element(1, Reason) =/= 'exit' ->
+                {error, Reason0} when not is_tuple(Reason0); element(1, Reason0) =/= 'exit' ->
+                    Reason =
+                        case Reason0 of
+                            {unhealthy_target, Message} -> Message;
+                            _ -> Reason0
+                        end,
                     ?BAD_REQUEST('TEST_FAILED', Reason)
             end;
         BadRequest ->

apps/emqx_bridge_gcp_pubsub/test/emqx_bridge_gcp_pubsub_consumer_SUITE.erl

@@ -1211,7 +1211,7 @@ t_nonexistent_topic(Config) ->
                 emqx_resource_manager:health_check(ResourceId)
             ),
             ?assertMatch(
-                {ok, _Group, #{error := "GCP PubSub topics are invalid" ++ _}},
+                {ok, _Group, #{error := {unhealthy_target, "GCP PubSub topics are invalid" ++ _}}},
                 emqx_resource_manager:lookup_cached(ResourceId)
             ),
             %% now create the topic and restart the bridge

apps/emqx_resource/src/emqx_resource_manager.erl

@@ -642,7 +642,6 @@ status_to_error(_) ->
     {error, undefined}.
 
 %% Compatibility
-external_error({error, {unhealthy_target, Message}}) -> Message;
 external_error({error, Reason}) -> Reason;
 external_error(Other) -> Other.