RangeArea Tooltips don't format datetime values

[delphi-sucks]

Description

When trying to use a RangeArea-Chart with a datetime-x-axis, the tooltip label for the x-axis doesn't get formatted like expected.

Steps to Reproduce

1. Create a RangeArea-Chart with datetime-Values for the x-axis
2. Set the x-axis type to datetime
3. Enable the tooltip
4. Hover over a datapoint to display the tooltip

Expected Behavior

The tooltip label for the x-axis gets formatted like the x-axis label.

Actual Behavior

The tooltip label for the x-axis just gets casted to string.

Screenshots

Reproduction Link

https://codepen.io/moddesteni/pen/eYKrYJz

[denxorz]

Worked around it like this for now:

https://codepen.io/denxorz/pen/LYrBoEq

  tooltip: {
    y: {
      formatter: (val) => {
        return isNaN(+val)
          ? `${new Date(parseInt(val)).toLocaleDateString()}:`  // Date (as string)
          : +val;                                               // Value (as int)
      }
    }
  },