title: Uncaught TypeError: (intermediate value)(intermediate value)(intermediate value) is not a function
body: <p>I get this error when trying to plot the following chart:</p>
  
  <pre><code>var chart1 = c3.generate({
    bindto: '#chart1',
    data: {
      url: '../CSV/Chart_data/grade_year.csv',
      x: 'YEAR',
      type: 'bar',
    },
    size: {
      height: 370
    },
    grid: {
      y: {
        show: true,
        lines: [{
          value: 5,
          text: 'Passed grade'
        }, ]
      }
    },
    bar: {
      width: {
        ratio: 0.7
      }
    }
  });
  </code></pre>
  
  <p>The grade_year.csv file is:</p>
  
  <pre><code>AC_YEAR,MEAN
  2010,5.387
  2011,5.63
  2012,5.258
  2013,5.355
  2014,5.235
  2015,4.892
  </code></pre>
  
  <p>I do not understand what is wrong... The complete error that I get is:</p>
  
  <blockquote>
    <p>c3.js:1097 Uncaught TypeError: (intermediate value)(intermediate value)(intermediate value) is not a function
        at ChartInternal.c3_chart_internal_fn.initParams (c3.js:1097)
        at ChartInternal.c3_chart_internal_fn.init (c3.js:1065)
        at new Chart (c3.js:1018)
        at Object.c3.generate (c3.js:1043)
        at Charts.js:1</p>
  </blockquote>