In Charter, I get divide by zero exception when y values are zero. Here is an example
to reproduce the bug:

| b data minDate view color |
    view := RTView new.
    b := RTCharterBuilder new.
    b view: view.
    b extent: 400 @ 200.
    data := {DateAndTime now -> 0 . DateAndTime now + 200 -> 0} asDictionary.
    minDate := data keys min.
    color := Color random.

    b interaction popupText: [:each | each ] .
    b shape ellipse
        size: 10;
        color: color.
    b points: data keys.
    b
        x: [ :aDate | aDate asUnixTime - minDate asUnixTime ];
        y: [ :each | data at: each ].
    b connectDotColor: color.
    b axisConfiguration
        labelRotation: -30;
        minValue: 1000;
        numberOfTicks: data keys size -1;
        labelConvertion: [ :v | (DateAndTime fromUnixTime: (v + minDate asUnixTime)) asDate].
    b axisX.
    b build.