Empty datum name breaks chart generation

[piotrp]

Description

Bug 1: using empty string as datum name breaks chart generation ("Uncaught TypeError: box is undefined").
Bug 2: using space character (0x20) as datum name makes legend item almost unclickable:

Using empty name makes little sense, but when using external data it may appear. Currently I'm guarding against it by replacing empty string with non-breaking space (\u00a0).

Steps to check or reproduce

JSFiddle: https://jsfiddle.net/tdnp2hfv/

Running:

bb.generate({
  data: {
    columns: [
	["data1", 30, 200, 100, 400, 150, 250],
	["", 50, 20, 10, 40, 15, 25]
    ],
    type: "line"
  },
  bindto: "#lineChart"
});

Results in:

Uncaught TypeError: box is undefined
updatePositions https://naver.github.io/billboard.js/release/3.5.1/dist/billboard.js:7522
updateLegendElement https://naver.github.io/billboard.js/release/3.5.1/dist/billboard.js:7688
each https://d3js.org/d3.v7.min.js:2
updateLegendElement https://naver.github.io/billboard.js/release/3.5.1/dist/billboard.js:7687
updateLegend https://naver.github.io/billboard.js/release/3.5.1/dist/billboard.js:7128
initLegend https://naver.github.io/billboard.js/release/3.5.1/dist/billboard.js:7098
initWithData https://naver.github.io/billboard.js/release/3.5.1/dist/billboard.js:11270
initToRender https://naver.github.io/billboard.js/release/3.5.1/dist/billboard.js:11095
runFn https://naver.github.io/billboard.js/release/3.5.1/dist/billboard.js:4071
convertData https://naver.github.io/billboard.js/release/3.5.1/dist/billboard.js:4362
initToRender https://naver.github.io/billboard.js/release/3.5.1/dist/billboard.js:11092
init https://naver.github.io/billboard.js/release/3.5.1/dist/billboard.js:11054
Chart https://naver.github.io/billboard.js/release/3.5.1/dist/billboard.js:13125
generate https://naver.github.io/billboard.js/release/3.5.1/dist/billboard.js:26013
https://fiddle.jshell.net/_display/?editor_console=true:114

[netil]

Hi @piotrp, thanks for the report. But what will be the use case of it?
Every data should have name to be distinguished among multiple data series. Is kinda counter intuitive.

[piotrp]

I'm displaying values coming from server logs, e.g. counts of HTTP Referer header. Empty string is not a sane value, but it may appear, and I hit this error when testing various edge cases.

I fully agree that this is not something that should be present in data. My main issue here is that a valid string input breaks chart completely (empty string) or causes degraded user experience (space).

[netil]

well, in that case to not break, data.idConverter option can be used.
But, unfortunately there's bug(#2808) for now. When the issue is fixed, you can handle empty data name as:

data: {
   idConverter: function(id) {
       return id === "" ? " " : id;
   }
}

[piotrp]

Thanks, that's certainly a better workaround, but even then an empty string shouldn't completely break the API.