fix: silently ignore a verticle animation when no item (#3757)

If when the verticleAnimationFrame callback fires, and the item no longer exists, (it has no parent), then we need to silently ignore that frame

lib/timeline/Core.js

@@ -137,7 +137,7 @@ Core.prototype._create = function (container) {
   // emitted via emitter
   this.hammer = new Hammer(this.dom.root);
   var pinchRecognizer = this.hammer.get('pinch').set({enable: true});
-  hammerUtil.disablePreventDefaultVertically(pinchRecognizer);
+  pinchRecognizer && hammerUtil.disablePreventDefaultVertically(pinchRecognizer);
   this.hammer.get('pan').set({threshold:5, direction: Hammer.DIRECTION_HORIZONTAL});
   this.listeners = {};
 

lib/timeline/Timeline.js

@@ -448,6 +448,10 @@ Timeline.prototype.focus = function(id, options) {
     var verticalAnimationFrame = function(ease, willDraw, done) {
       var verticalScroll = getItemVerticalScroll(me, item);
 
+      if (verticalScroll === false) {
+        return; // We don't need to scroll, so do nothing
+      }
+
       if(!initialVerticalScroll) {
         initialVerticalScroll = verticalScroll;
       }
@@ -560,6 +564,11 @@ function getEnd(item) {
  * @return {{shouldScroll: bool, scrollOffset: number, itemTop: number}}
  */
 function getItemVerticalScroll(timeline, item) {
+  if (!item.parent) {
+    // The item no longer exists, so ignore this focus.
+    return false;
+  }
+
   var leftHeight = timeline.props.leftContainer.height;
   var contentHeight = timeline.props.left.height;
   

test/Timeline.test.js

@@ -0,0 +1,44 @@
+var DataSet = require('../lib/DataSet');
+var Timeline = require('../lib/timeline/Timeline');
+
+describe('Timeline', function () {
+	before(function () {
+		this.jsdom = require('jsdom-global')({
+			pretendToBeVisual: true
+		});
+		global['Element'] = window.Element;
+		global['requestAnimationFrame'] = function(cb) {
+			cb();
+		};
+	});
+
+	after(function () {
+		this.jsdom();
+	});
+
+	it('should not throw when updating data in close succession', function (done) {
+		var timeline = new Timeline(document.createElement('div'), []);
+
+		var events = [
+			{start: new Date(), id: 1},
+			{start: new Date(), id: 2}
+		];
+
+		timeline
+			.setItems(new DataSet(events));
+
+		setTimeout(function() {
+			timeline
+				.setItems(new DataSet([
+					{start: new Date(), id: 3},
+					{start: new Date(), id: 4},
+					{start: new Date(), id: 5}
+				]));
+
+			done();
+		}, 5);
+
+		timeline
+			.setSelection([events[0].id], {animation: false});
+	});
+});