No color gradient rending about grafana-diagram HOT 1 CLOSED

I traced the following in diagramControl.js, onDataReceived() when bug is present :

onDataReceived(dataList)
=> this.setValues(data)
=> this.getGradientForValue(data[seriesItem.alias].colorData, data[seriesItem.alias].value);
=> getColorByXPercentage(this.canvas, xPercent);
=> context.getImageData(x, 1, 1, 1).data; returns [0, 0, ....0]

It seems the canvas content is set up later, during render().
If I edit the diagram parameters, changing a threshold for example, it will get correct values.

from grafana-diagram.