How to set new Sequence of the index while creating a new row in a table?

Question

In the following example below, I create a new table with a custom column named label, which is, literally, the index of the gridRow array of objects.

I faced a problem while trying to create a new row which is inserted before the last element, (before last object in my case).

And there came the problem with not getting in the sequence of the label/index.

Codesandbox demo

import React from "react";
import { AgGridReact } from "ag-grid-react";
import "ag-grid-community/dist/styles/ag-grid.css";
import "ag-grid-community/dist/styles/ag-theme-alpine.css";
function App() {
  const [gridApi, setGridApi] = React.useState(null);
  const [gridColumnApi, setGridColumnApi] = React.useState(null);

  const onGridReady = (params) => {
    setGridApi(params.api);
    setGridColumnApi(params.columnApi);
  };

  const defaultColDef = {
    flex: 1,
    editable: true
  };

  const columnDefs = [
    {
      headerName: "label",
      field: "label"
    },
    {
      headerName: "Name",
      field: "name"
    },
    { headerName: "stop", field: "stop" },
    {
      headerName: "duration",
      field: "duration"
    }
  ];
  const rowData = React.useMemo(
    () => [
      {
        name: "John",
        stop: 10,
        duration: 5
      },
      {
        name: "David",
        stop: 15,
        duration: 8
      },
      {
        name: "Dan",
        stop: 20,
        duration: 6
      }
    ],
    []
  );

  const rowDataWithIndex = React.useMemo(() => {
    return (
      rowData &&
      rowData.map((row, index) => ({
        ...row,
        label: index
      }))
    );
  }, [rowData]);

  const addNewRow = () => {
    gridApi.applyTransaction({
      add: [{ label: rowDataWithIndex[rowDataWithIndex.length - 2].label + 1 }],
      addIndex: rowDataWithIndex.length - 1
    });
  };

  return (
    <div>
      <h1 align="center">React-App</h1>
      <div>
        <button onClick={addNewRow}>New Row</button>
        <div className="ag-theme-alpine">
          <AgGridReact
            columnDefs={columnDefs}
            rowData={rowDataWithIndex}
            defaultColDef={defaultColDef}
            domLayout={"autoHeight"}
            onGridReady={onGridReady}
          ></AgGridReact>
        </div>
      </div>
    </div>
  );
}

export default App;

Any help will be appreciated