How to fix error when querying mongodb?

Question

Node.js

Good afternoon. I have a collection

doing sorting. I count the number of duplicates and the sum of the package sizes (Size). Then I write to another collection. Here's what I get

How do I put the sum of the packets, now this is the (count) field in the Size field? and remove the count field so that it is like this

Here is my code. I don't understand what needs to be changed?

var ss = mongoQLog.aggregate([ {
    $group: { _id: { name: "$ip", value: "$port2", value2:"$protocol"},
      doc: { $last: "$$ROOT" }, // Retrieve only last doc in a group
      count:{$sum:"$size"},
      total:{$sum:1}
      
    }
  },
  {
      
    $replaceRoot: { newRoot: { $mergeObjects: [{ count: '$count',total:"$total" }, '$doc'] }} // replace doc as object as new root of document
  },
  { $out : 'collection_new' }]).exec(function ( e, d ) {
        
});