ChartJS instance always returns null

[JoaoHCopetti]

I just can't get the chart instance in Vue ChartJS, it always returns null.

• Vue: 2.7
• Vue ChartJS: 5.2.0
• ChartJS: 4.3.3

import { Line as LineChart } from 'vue-chartjs'
import { Chart as ChartJS, Tooltip, CategoryScale, LinearScale, PointElement, LineElement, Legend } from 'chart.js'
import zoomPlugin from 'chartjs-plugin-zoom'

ChartJS.register(CategoryScale, Legend, Tooltip, LinearScale, PointElement, LineElement, zoomPlugin)

<script>
export default {
  components: {
    LineChart
  },
  methods: {
    test () {
      this.$refs.lineChart.chart // null
      this.$refs.lineChart.chartInstance // null too
    }
  }
}
</script>

<template>
  <LineChart
    id="my-chart-id"
    ref="lineChart"
  />
</template>