zoom with type 'drag': $$.unexpandBars is not a function

[Nicolas469]

Description

Can't zoom with type 'drag'.

Steps to check or reproduce

A) Billboard imported in a Angular project with npm i billboard.js

B) import bb, { bar as bbBar, line as bbLine, subchart as bbSubchart, zoom as bbZoom } from 'billboard.js';

bb.generate({
  data: {
    columns: [['sample', 30, 200, 100, 400, 150, 250]],
    type: bbLine()
  },
  zoom: {
    enabled: bbZoom(),
    type: 'drag'
  },
  bindto: `#chart-${this.chartAreaId}`
});

C) Zoom on chart
D) This will not zoom and will display an error in console:

core.js:4352 ERROR TypeError: $$.unexpandBars is not a function
    at Chart.hide (billboard.esm.js:8900)
    at Chart.zoom (billboard.esm.js:17396)
    at SVGGElement.<anonymous> (billboard.esm.js:18475)
    at Dispatch.apply (dispatch.js:61)
    at customEvent (on.js:103)
    at Object.gesture (drag.js:137)
    at mouseupped (drag.js:76)
    at on.js:27
    at ZoneDelegate.invokeTask (zone.js:407)
    at Object.onInvokeTask (core.js:27474)

## [Part of] Solution
billboard.esm.js:8900: change
        $$.unexpandCircles();
        $$.unexpandBars();
and put
        $$.unexpandCircles && $$.unexpandCircles();
        $$.unexpandBars && $$.unexpandBars();

since unexpandBars() is defined only for bar chart (the same thing can append with unexpandCircles()).

[netil]

Hi @Nicolas469, thanks for report!