show datapoints with 0 downloads

[miDeb]

Dates with zero downloads are not included in the downloaded data, so
we have to insert new datapoints between the other datapoints.

[klausenbusk]

Chart.js has a spanGaps option:

If true, lines will be drawn between points with no or null data. If false, points with null data will create a break in the line. Can also be a number specifying the maximum gap length to span. The unit of the value depends on the scale used.

Wouldn't that be a simpler solution?

[miDeb]

I'm not sure that would work better, because it would create gaps instead of connecting a line to 0, and we would still have to insert data points with a null value where the gap should be. I think it's easier to insert data points with a value of 0 and not use this option.