Failed assertion: line 1702 pos 12: 'center!.parent == this': is not true

Question

What is the reason for getting the error?

And when I put the debug flag in the Streambuilder line, my application freezes before it comes to the main screen.

body: CustomScrollView(
        slivers: [
          StreamBuilder<QuerySnapshot>(
            stream: FirebaseFirestore.instance
                .collection('posts')
                .limit(10)
                .orderBy('id', descending: true)
                .snapshots(),
            builder: (BuildContext context,
                AsyncSnapshot<QuerySnapshot> dataSnapshot) {
              return !dataSnapshot.hasData
                  ? SliverToBoxAdapter(
                      child: linearProgress(),
                    )
                  : SliverStaggeredGrid.countBuilder(
                      crossAxisCount: 1,
                      staggeredTileBuilder: (val) => StaggeredTile.fit(1),
                      itemBuilder: (context, index) {
                        DataModel model = DataModel.fromJson(
                            dataSnapshot.data!.docs[index].data()
                                as Map<String, dynamic>);
                        return sourceInfo(model, context);
                      },
                      itemCount: dataSnapshot.data!.docs.length);
            },
          ),
        ],
      ),

There was no problem when I imported the relevant codes into SliverPadding. Edited code.

StreamBuilder<QuerySnapshot>(
            stream: FirebaseFirestore.instance
                .collection('posts')
                .limit(10)
                .orderBy('id', descending: true)
                .snapshots(),
            builder: (BuildContext context,
                AsyncSnapshot<QuerySnapshot> dataSnapshot) {
              return !dataSnapshot.hasData
                  ? SliverPadding(
                sliver: SliverToBoxAdapter(
                  child: ColorLoader(),
                ),
                padding: EdgeInsets.all(0),
              )
                  : SliverPadding(
                sliver: SliverStaggeredGrid.countBuilder(
                    crossAxisCount: 1,
                    staggeredTileBuilder: (_) => StaggeredTile.fit(1),
                    itemBuilder: (context, index) {
                      DataModel model = DataModel.fromJson(
                          dataSnapshot.data!.docs[index].data()
                          as Map<String, dynamic>);
                      return sourceInfo(model, context);
                    },
                    itemCount: dataSnapshot.data!.docs.length),
                padding: EdgeInsets.all(0),
              );
            },
          ),

Solution

According to this comment in a Github thread for a similar issue if the sliver being replaced is not the first it should work fine.

So a possible workaround is to add empty SliverToBoxAdapter() as first sliver before BodyContent().

There is more information and possible solutions in the Github thread, I recommend taking a look at it.