docs: @SuppressWarnings("WeakerAccess")
      @UiThread
      public boolean popCurrentController() {
          ThreadUtils.ensureMainThread();
  
          RouterTransaction transaction = backstack.peek();
          if (transaction == null) {
              throw new IllegalStateException("Trying to pop the current controller when there are none on the backstack.");
          }
          return popController(transaction.controller);
      }