title: Line series graphs gives error on resizing - highcharts
body: <p>I have used highcharts <a href="https://i.stack.imgur.com/t3iFU.png" rel="nofollow noreferrer">single line series graph</a>. It seems to work all fine but when I resize the page (just to check responsiveness or just it on mobile). The values disappear. I can see error in console logs. </p>
  
  <p><a href="https://i.stack.imgur.com/t3iFU.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/t3iFU.png" alt="enter image description here"></a></p>
  
  <p>That's how I generate the chart</p>
  
  <pre><code>Highcharts.stockChart('nav-chart', {
  
   tooltip: {
          pointFormat:"{point.y:.3f}\u20ac"
    },
    chart: {
      type: 'line',
      zoomType: 'x',
      pinchType: 'x',
      panning: false,
      &lt;?php if (is_front_page()){ ?&gt;
      height: 700,
      &lt;?php } else { ?&gt; 
      height: 500, 
      events: {
        load: updateLegendLabel 
      }    
      &lt;?php } ?&gt; 
    },
  </code></pre>
  
  <p><code>updateLegendLabel</code> has some computation that generates the labels. </p>
  
  <pre><code> var chrt = !this.chart ? this : this.chart;
    chrt.update({
      legend: {
        useHTML: true,
        symbolPadding: 0,
        symbolWidth: 0,
        symbolHeight: 0,
        symbolRadius: 0,    
        labelFormatter: function() {
  
  
          var lastVal = this.yData[this.yData.length - 1],
            chart = this.chart,
            xAxis = this.xAxis,
            points = this.points,
            avg = 0,
            counter = 0,
            min, max;
  ... there is some business logic down there
  </code></pre>
  
  <p><code>points</code> var becomes null when I resize the page. Why is that so? Do I need to reupdate dataset or what?</p>