Legend disappears when hiding single series chart

[Alex-Sokolov]

Codepen
vue-apexcharts codesandbox: https://codesandbox.io/s/vue-basic-example-6o79g

apexcharts: 3.8.5
vue-apexcharts: 1.5.0

Legend options:

legend: {
          show: true,
          showForSingleSeries: true,
          showForNullSeries: true,
          showForZeroSeries: true,
        }

Explanation
In our application, data sets are added dynamically. By default, there is only one data set. If you click on it in legend, then in addition to hiding the set, the legend itself disappears instead of becoming semi-transparent item in legend