title: Insert rows and columns in google chart dataTable
body: <p>i have proble with google charts api. I need insert columns and rows in data table preloaded chart. </p>
  
  <p>When execute updateChart() i have this error: Uncaught Error: Every row given must be either null or an array.</p>
  
  <p>And here is my code</p>
  
  <pre><code>google.load("visualization", "1", {packages:["corechart"]});
    google.setOnLoadCallback(drawChart);
    function drawChart() {
      var data = new google.visualization.DataTable();
  
      data.addColumn('string', 'Year');
      data.addColumn('number', 'Sales');
      data.addColumn('number', 'Expenses');
  
  
  
      data.addRows([
      ['2004', 1000, 400],
      ['2005', 1170, 460],
      ['2006',  860, 580],
      ['2007', 1030, 540]
      ]);
  
      var options = {
        title: 'Company Performance'
      };
  
      var chart = new google.visualization.LineChart(document.getElementById('chart_div'));
      chart.draw(data, options);
    }      
    function updateChart() {
  
        data.insertColumn(3, 'number', 'Other');
        data.insertRows(3, [800,600,400,300])
  
    }
  </code></pre>