This isn't an ampersand bug, it's an Edge bug. And I think it was reported here: https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/9628212/
That glitch indicates that the state of options elements in a select object aren't updated immediately in Microsoft Edge. This behaviour is confirmed by Microsoft Edge team and, until they fix it, produces an error here:
206 this.getAllOptions().forEach(function(v,i) {
207 this.select.options[i].selected = false;
208 }.bind(this));
Line 207 appears to fail in Microsoft Edge. this.select.childNodes.length and this.select.options.length will be temporarily different while the options are enumerated and deselected by the loop above. Then subsequent code will proceed (and fail).