fix: <rect> attribute width bug

Hidden elements have zero width, subtracting offset would make the width negative.
These negative values would cascade down to component creation

src/js/charts/BaseChart.js

@@ -1,5 +1,5 @@
 import SvgTip from '../objects/SvgTip';
-import { $, isElementInViewport, getElementContentWidth } from '../utils/dom';
+import { $, isElementInViewport, getElementContentWidth, isHidden } from '../utils/dom';
 import { makeSVGContainer, makeSVGDefs, makeSVGGroup, makeText } from '../utils/draw';
 import { BASE_MEASURES, getExtraHeight, getExtraWidth, getTopOffset, getLeftOffset,
 	INIT_CHART_UPDATE_TIMEOUT, CHART_POST_ANIMATE_TIMEOUT, DEFAULT_COLORS} from '../utils/constants';
@@ -134,6 +134,10 @@ export default class BaseChart {
 	bindTooltip() {}
 
 	draw(onlyWidthChange=false, init=false) {
+		if (onlyWidthChange && isHidden(this.parent)) {
+			// Don't update anything if the chart is hidden
+			return;
+		}
 		this.updateWidth();
 
 		this.calc(onlyWidthChange);

src/js/utils/dom.js

@@ -54,6 +54,13 @@ export function getOffset(element) {
 	};
 }
 
+// https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/offsetParent
+// an element's offsetParent property will return null whenever it, or any of its parents,
+// is hidden via the display style property.
+export function isHidden(el) {
+	return (el.offsetParent === null);
+}
+
 export function isElementInViewport(el) {
 	// Although straightforward: https://stackoverflow.com/a/7557433/6495043
 	var rect = el.getBoundingClientRect();