chore: Add error message if canvas is not found due to overwritten template

Author: apertureless

src/BaseCharts.js

@@ -69,6 +69,7 @@ export function generateChart (chartId, chartType) {
       },
       renderChart (data, options) {
         if (this.$data._chart) this.$data._chart.destroy()
+        if (!this.$refs.canvas) throw new Error('Please remove the <template></template> tags from your chart component. See https://vue-chartjs.org/guide/#vue-single-file-components')
         this.$data._chart = new Chart(
           this.$refs.canvas.getContext('2d'), {
             type: chartType,