createRenderer method Null safety

WaterfallSeriesRenderer createRenderer(
  1. ChartSeries<T, D> series

Create the waterfall series renderer.


WaterfallSeriesRenderer createRenderer(ChartSeries<T, D> series) {
  WaterfallSeriesRenderer seriesRenderer;
  if (onCreateRenderer != null) {
    seriesRenderer = onCreateRenderer!(series) as WaterfallSeriesRenderer;
    // ignore: unnecessary_null_comparison
    assert(seriesRenderer != null,
        'This onCreateRenderer callback function should return value as extends from ChartSeriesRenderer class and should not be return value as null');
    return seriesRenderer;
  return WaterfallSeriesRenderer();