src/vs/workbench/browser/parts/views/viewsService.ts/ViewsService/deregisterViewletOrPanel
class ViewsService:	private deregisterViewletOrPanel(viewContainer: ViewContainer, viewContainerLocation: ViewContainerLocation): void {
		switch (viewContainerLocation) {
			case ViewContainerLocation.Panel:
				this.deregisterPanel(viewContainer);
				break;
			case ViewContainerLocation.Sidebar:
				if (viewContainer.ctorDescriptor) {
					this.deregisterViewlet(viewContainer);
				}
				break;
		}
	}