title: Google Charts: Cannot read property '0' of undefined
body: <p>I cannot seem to get google charts working with JSON data.
  I get this error: <strong>'Cannot read property '0' of undefined.'</strong>
  The JSON response DOES have a JSON content type set. I've looked around at similar questions but cannot seem to find any solution. </p>
  
  <p><strong>Javascript:</strong></p>
  
  <pre><code>google.load('visualization', '1', {
    packages: ['corechart']
  });
  google.setOnLoadCallback(get_data);
  
  function get_data() {
    $.getJSON('/api?data=graphs', function(json) {
      var status = json.status;
      render_chart(status);
    });
  }
  
  function render_chart(status) {
    var status_chart = new google.visualization.DataTable(status);
    var options_status_chart = {
      lineWidth: 0,
      areaOpacity: 0.5
    }
  }
  </code></pre>
  
  <p><strong>JSON Response:</strong></p>
  
  <pre><code>{
    "status": {
       "cols": [{
          "type": "string",
          "label": "Date - Time",
          "id": "dt_metric"
       }, {
          "type": "number",
          "label": "Status",
          "id": "s_metric"
       }],
       "rows": [{
          "c": [{
             "v": "2016\/1\/5 - 09:30"
          }, {
             "v": 0
          }]
       }, {
          "c": [{
             "v": "2016\/1\/5 - 10:00"
          }, {
             "v": 1
              }]
           }]
      }
  }
  </code></pre>