recovery doesn't work with prometheus

[frostbyte73]

I'm trying to get prometheus to report recovered panics, but it seems it doesn't work, regardless of middleware order.

Simple example:

opts := []grpc.ServerOption{
	grpc_middleware.WithStreamServerChain(
		grpc_recovery.StreamServerInterceptor(),
		grpc_prometheus.StreamServerInterceptor,
	),
	grpc_middleware.WithUnaryServerChain(
		grpc_recovery.UnaryServerInterceptor(),
		grpc_prometheus.UnaryServerInterceptor,
	),
}

grpcServer := grpc.NewServer(opts...)
myService.RegisterMyServiceServer(grpcServer, &myServer{})
grpc_prometheus.Register(grpcServer)
// ... handle /metrics for prometheus, serve grpc server

When myService.MyMethod panics, it correctly returns a grpc internal error, but prometheus reads grpc_server_handled_total{grpc_code="Internal",grpc_method="MyMethod",grpc_service="myService.MyService",grpc_type="unary"} 0

I know prometheus is working, because grpc_server_msg_received_total shows the correct count - it's just missing from the grpc_server_handled_total metrics.

Is there a way for the recovery to return an error which is then used by other middleware? I've tried swapping the order of recovery and prometheus, but got the same result.