I know it's been a while since this question was asked. But, I had the same problem last week and tried a ton of ways to fix it. In the end, all I had to do was change my weights from numeric to integer.

So, use class(data$weights) to check the class of your weights.

Then

data$weights<-as.integer(data$weights)

When I did that, the message stopped showing up.

Hope that helps!