bad confidence intervals

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.3/Chart.min.js"></script>
<canvas id="demo"></canvas>

JavaScript

var chartData = {
    labels: [1, 2, 3, 4, 5],
    datasets: [
			{
          label: "Set 1_lo",
          backgroundColor: 'rgba(55, 173, 221,  0.6)',
          data: [8, 18, 48, 38, 28],
          borderWidth: 0.1,
          fill: false,
          pointRadius: 0.0,
      },
    
      {
          label: "Set 1",
          backgroundColor: 'rgba(55, 173, 221,  1)',
          data: [10, 20, 50, 40, 30],
          borderColor: "#00F",
          fill: false,
          pointRadius: 0.0,
      },
      
      {
          label: "Set 1_hi",
          backgroundColor: 'rgba(55, 173, 221,  0.6)',
          data: [12, 22, 52, 42, 32],
          borderWidth: 0.1,
          fill: '-2',
          pointRadius: 0.0,
      },
			{
          label: "Set 2_lo",
          backgroundColor: 'rgba(221, 55, 173, 0.6)',
          data: [46, 37, 28, 9, 20],
          borderWidth: 0.1,
          fill: false,
          pointRadius: 0.0,
      },
    
      {
          label: "Set 2",
          backgroundColor: 'rgba(221, 55, 173, 1)',
          data: [50, 40, 30, 10, 20],
          borderColor: "#F00",
          fill: false,
          pointRadius: 0.0,
      },
      
      {
          label: "Set 2_hi",
          backgroundColor: 'rgba(221, 55, 173, 0.6)',
          data: [50, 41, 32, 13, 24],
          borderWidth: 0.1,
          fill: '-2',
          pointRadius: 0.0,
      },
    ]
};

var chartOptions = {
    responsive: true,
    title: {
        display: true,
        text: 'Bad Confidence Intervals'
    },
      legend: {
        display: true,
        // this toggles on / off the confidence intervals
        labels: {
          filter: function(item, chart) {
            return !item.text.includes('_');
          }
        },
       onClick: function(e, legendItem) { // need to hide index -1 and index +1
          var index = legendItem.datasetIndex;
          var ci = this.chart;
          var alreadyHidden = (ci.getDatasetMeta(index).hidden === null) ? false :...