title: Making Background blur upon clicking FabCircularMenu in Flutter
body: <p>The idea is to toggle the screen between normal and blur upon clicking the FabCircularMenu. However, I keep running into a Null Safety check error every time I try doing so, and by far, the auto-suggestions have not worked. My code is below:</p>
  <pre><code>class _StoryScreenState extends State&lt;StoryScreen&gt;
      with SingleTickerProviderStateMixin {
    final GlobalKey&lt;FabCircularMenuState&gt; fabKey = GlobalKey();
       @override
        Widget build(BuildContext context) {
          final Story story = widget.stories![_currentIndex];
          final height = MediaQuery.of(context).size.height;
          final width = MediaQuery.of(context).size.width;
      
          return Scaffold(
            floatingActionButton: FabCircularMenu(
              key: fabKey,
              // Cannot be `Alignment.center`
              alignment: Alignment.bottomRight,
              // ringColor: Colors.white.withOpacity(0.1),
              ringColor: Colors.transparent,
              ringDiameter: 200.0,
              ringWidth: 50.0,
              fabSize: MediaQuery.of(context).size.width * 0.12,
              fabElevation: 8.0,
              fabIconBorder: CircleBorder(),
              fabColor: Colors.white,
              fabOpenIcon: Center(
                child: SvgPicture.asset(
                  &quot;assets/svgs/filter-icon.svg&quot;,
                ),
              ),
      
              fabCloseIcon: SvgPicture.asset(&quot;assets/svgs/sideBar.svg&quot;),
              fabMargin: const EdgeInsets.all(16.0),
              animationDuration: const Duration(milliseconds: 1000),
              animationCurve: Curves.easeInOutBack,
      
              children: &lt;Widget&gt;[
                Padding(
                  padding: EdgeInsets.only(top: height * 0.04),
                  child: RawMaterialButton(
                    elevation: 5,
                    onPressed: () {
                      // _showSnackBar(context, &quot;You pressed 1&quot;);
                    },
                    shape: CircleBorder(),
                    // padding: const EdgeInsets.all(10.0),
                    child:
                        SvgPicture.asset(&quot;assets/svgs/ll.svg&quot;, height: 45, width: 45),
                  ),
                ),
                Padding(
                  padding: EdgeInsets.only(top: height * 0.02),
                  child: RawMaterialButton(
                    onPressed: () {
                      // _showSnackBar(context, &quot;You pressed 2&quot;);
                    },
                    shape: CircleBorder(),
                    // padding: const EdgeInsets.all(10.0),
                    elevation: 5,
                    child: SvgPicture.asset(&quot;assets/svgs/filter-01.svg&quot;,
                        height: 50, width: 50),
                  ),
                ),
                Padding(
                  padding: EdgeInsets.only(left: width * 0.04, top: height * 0.005),
                  child: RawMaterialButton(
                    shape: CircleBorder(),
                    // padding: const EdgeInsets.all(10.0),
                    elevation: 5,
                    child: SvgPicture.asset(&quot;assets/svgs/location.svg&quot;,
                        height: 50, width: 50),
                  ),
                ),
                Padding(
                  padding: EdgeInsets.only(left: width * 0.08, top: height * 0.015),
                  child: RawMaterialButton(
                    onPressed: () {
                      setState(() {
                        _isButtonPreesd = !_isButtonPreesd;
                      });
                    },
                    shape: CircleBorder(),
                    // padding: const EdgeInsets.all(10.0),
                    elevation: 5,
                    child: SvgPicture.asset(&quot;assets/svgs/heart.svg&quot;,
                        height: 45, width: 45),
                  ),
                )
              ],
            ),
            // backgroundColor: Colors.black,
            body:
                //This is where the error gets thrown. The open method shows a red line underneath it. The warning is given below
                fabKey.currentState!.open()  
                    ? Stack(                     //Logic to fade out the screen
                        fit: StackFit.expand,
                        children: [
                          Image.asset('assets/images/filter.png', fit: BoxFit.cover),
                          ClipRRect(
                            // Clip it cleanly.
                            child: BackdropFilter(  
                              filter: ImageFilter.blur(sigmaX: 10, sigmaY: 10),
                              child: Container(),
                            ),
                          ),
                        ],
                      )
                    : Stack(.........)
  </code></pre>
  <p>This is what the error at the line says:</p>
  <pre><code>This expression has a type of 'void' so its value can't be used.
  Try checking to see if you're using the correct API; there might be a function or call that returns void you didn't expect. Also check type parameters and variables which might also be void.
  </code></pre>
  <p>Any ideas on how I can get it to work properly. I'm a little blank at the moment and still totally out of ideas as to how this can be made null safe.</p>