Error:

════════ Exception caught by widgets library ═══════════════════════════════════ The method ‘countBuilder’ was called on null. Receiver: null Tried calling: countBuilder(crossAxisCount: 4, crossAxisSpacing: 4, itemBuilder: Closure: (BuildContext, int) => DoctorBox, itemCount: 246, mainAxisSpacing: 4, physics: Instance of ‘NeverScrollableScrollPhysics’, shrinkWrap: true, staggeredTileBuilder: Closure: (int) => dynamic)

The relevant error-causing widget was:

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In my case:

The error message “Method ‘countBuilder’ was called on null” typically occurs when a method or property is being accessed on a null object. In Flutter, this often happens when trying to access properties or methods of widgets that haven’t been properly initialized or when attempting to use widgets that are null.

if (filteredDoctors.isNotEmpty)

              getDoctorList()

            else if (searchController.text.isNotEmpty)

              const Center(

                child: Text('No matching doctors found'),

              ),

getDoctorList() {
    final filteredDoctors = searchController.text.isNotEmpty
        ? searchDoctors(searchController.text)
        : doctors;

    return StaggeredGridView.countBuilder(
      shrinkWrap: true,
      physics: const NeverScrollableScrollPhysics(),
      crossAxisCount: 4,
      itemCount: filteredDoctors.length,
      itemBuilder: (BuildContext context, int index) => DoctorBox(
        onTap: () {
          Navigator.push(
            context,
            MaterialPageRoute(
              builder: (BuildContext context) =>
                  DoctorProfilePage(doctor: filteredDoctors[index]),
            ),
          );
        },
        index: index,
        doctor: filteredDoctors[index],
      ),
      staggeredTileBuilder: (int index) =>
          StaggeredTile.count(2, index.isEven ? 2 : 3),
      mainAxisSpacing: 4,
      crossAxisSpacing: 4,
    );
  }

After changing

      // Display either the StaggeredGridView or a "No data available" message
            if (filteredDoctors.isNotEmpty)
              getDoctorList(filteredDoctors)
            else if (searchController.text.isNotEmpty)
              const Center(
                child: Text('No matching doctors found'),
              ),
          ],
        ),
      ),
    );
  }

  Widget getDoctorList(List<dynamic> filteredDoctors) {
    final filteredDoctors = searchController.text.isNotEmpty
        ? searchDoctors(searchController.text)
        : doctors;

    return StaggeredGridView.countBuilder(
      shrinkWrap: true,
      physics: const NeverScrollableScrollPhysics(),
      crossAxisCount: 4,
      itemCount: filteredDoctors.length,
      itemBuilder: (BuildContext context, int index) => DoctorBox(
        onTap: () {
          Navigator.push(
            context,
            MaterialPageRoute(
              builder: (BuildContext context) =>
                  DoctorProfilePage(doctor: filteredDoctors[index]),
            ),
          );
        },
        index: index,
        doctor: filteredDoctors[index],
      ),
      staggeredTileBuilder: (int index) =>
          StaggeredTile.count(2, index.isEven ? 2 : 3),
      mainAxisSpacing: 4,
      crossAxisSpacing: 4,
    );
  }

hope