src/vs/workbench/services/views/common/viewContainerModel.ts/ViewContainerModel/find
class ViewContainerModel:	private find(id: string): { index: number, visibleIndex: number, viewDescriptorItem: IViewDescriptorItem; } {
		const result = this.findAndIgnoreIfNotFound(id);
		if (result) {
			return result;
		}
		throw new Error(`view descriptor ${id} not found`);
	}