[Bug] Line graph with Y axis "category" renders null values incorrectly

[htr3n]

Version

5.3.1

Link to Minimal Reproduction

https://codesandbox.io/s/echarts-category-83rl4d?file=/src/index.js

Steps to Reproduce

1. Create a simple line chart with the following options

import * as echarts from "echarts";

const chart = echarts.init(document.getElementById("chart"));

const options = {
  animation: false,
  xAxis: {
    type: "category",
    splitLine: { show: true },
    data: ["1:00", "2:00", "3:00", "4:00", "5:00"]
  },
  yAxis: {
    type: "category",
    axisLabel: {
      show: true
    },
    showMinLabel: true,
    showMaxLabel: true,
    data: ["A", "B", "C"]
  },
  series: [
    {
      type: "line",
      data: ["null", "A", undefined, "C", null],
      symbol: "circle",
      showSymbol: true,
      symbolSize: 8,
      lineStyle: {
        opacity: 0
      },
      connectNulls: false
    }
  ]
};
chart.setOption(options);

Current Behavior

The chart is rendered correctly with respect to valid values (e.g. the values that are defined in the Y axis data parameter) and "null" (note that null in double quotes as a string) but incorrectly regarding the native JavaScript null value. For instance, in the included example, the last three values are JavaScript native null has been rendered as legit ones with the dots at the value A.

Expected Behavior

The chart should not render any dots regarding the input data null (without double quotes).

Surprisingly, ECharts renders correctly the value "null" (null inside double quotes as a legit JS string, not the native null value).

Another note, ECharts renders correctly if the input data is the native JS undefined value.

Environment

- OS: N/A
- Browser: N/A
- Framework: N/A

Any additional comments?

No response

[WindyZ99]

I'm interested in fixing it.

[htr3n]

@pissang Is this bugfix included in any release or just the nightly builds? Thanks.