`panel` widget gets rendered even when `renderPanelSheet` is false

Describe the bug I want different widgets to be displayed when the panel is collapsed and expanded. According to the README, renderPanelSheet should be set to false to achieve the expected behavior. Yet, it renders both panel widget and collapsed on top of one another.

To Reproduce Can use a code similar to the one below. Click here for complete code.

     return SlidingUpPanel(
      collapsed: CollapsedControls(),
      renderPanelSheet: false,
      controller: panelController,
      minHeight: MediaQuery.of(context).size.height * 0.2,
      maxHeight: MediaQuery.of(context).size.height * 0.9,

      panel: ClipRRect(
        borderRadius: BorderRadius.only(
          topLeft: Radius.circular(20),
          topRight: Radius.circular(20),
        ),
        child: Container(
          decoration: BoxDecoration(
            color: Theme.of(context).backgroundColor.withOpacity(0.65),
          ),
          child: BackdropFilter(
            filter: new ImageFilter.blur(sigmaX: 20.0, sigmaY: 20.0),
            child: Column(
              children: [
                Container(
                  color: Colors.red,
                  height: 100,
                  width: 100,
                )
              ],
            ),
          ),
        ),
      ),
    );

Expected behavior The red square should appear only when the panel is opened.

Screenshots

Smartphone

Device: Pixel 4 Emulator
OS: Android 12 - SDK 31
Flutter Version 2.8.0
sliding_up_panel Version 2.0.0+1

akshathjain / sliding_up_panel

`panel` widget gets rendered even when `renderPanelSheet` is false #284