TimeStamp not matching with missing data

[oscgonfer]

Hey,
I think there is a problem when the data in a comparison does not have both channels in the selected timeframe:

[oscgonfer]

To add up on this:

You can reproduce by visiting device: https://smartcitizen.me/kits/12499
The issue seems to be due to the visualization cursor being created by rank index, instead of timestamp index:

On

smartcitizen-web/src/app/components/chart/chart.directive.js

Lines 509 to 517 in a6623d5

	function mousemove() {
	var bisectDate = d3.bisector(function(d) { return d.date; }).left;
	var x0 = xScale.invert(d3.mouse(this)[0]);
	var i = bisectDate(data[1], x0, 1);
	var d0 = data[1][i - 1];
	var d1 = data[1][i];
	var d = x0 - d0.date > d1.date - x0 ? d1 : d0;
	focusCompare.attr('transform', 'translate(' + xScale(d.date) + ', ' + yScale1(d.count) + ')');