Null Pointer exception is showing on the recyclerview

Question

I am trying to set the image slider in the recycler-view but it is throwing a null pointer exception. I have set the textviews and they are showing to the recyclerview but slider is not showing and throwing error. I am using dependency to use image-slider. I am new to android and I have no idea how can i solve this please guide me.

public class RecyclerviewAdapter extends RecyclerView.Adapter<RecyclerviewAdapter.Viewholder> {

ArrayList<RecyclerviewModel> datalist;
Context context;
final List<SlideModel> imagelist = new ArrayList<>();


public RecyclerviewAdapter(ArrayList<RecyclerviewModel> datalist, Context context) {
    this.datalist = datalist;
    this.context = context;
}

@NonNull
@Override
public Viewholder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

    View viewholder = LayoutInflater.from(parent.getContext()).inflate(R.layout.single_item, parent , false);

    return new Viewholder(viewholder);
}

@Override
public void onBindViewHolder(@NonNull Viewholder holder, int position)
{


    holder.name.setText(datalist.get(position).getName());
    holder.email.setText(datalist.get(position).getEmail());
    holder.desc.setText(datalist.get(position).getDesc());
    holder.book.setText(datalist.get(position).getBook());

    //code for set images in image slider from firebase firestore
    imagelist.add(new SlideModel(datalist.get(position).getImage().toString(), ScaleTypes.FIT));
    holder.imageSlider.setImageList(imagelist, ScaleTypes.FIT);

}


@Override
public int getItemCount() {
    return datalist.size();
}

public class Viewholder extends RecyclerView.ViewHolder{


    TextView name, email, desc, book;
    ImageSlider imageSlider;
    public Viewholder(@NonNull View itemView) {
        super(itemView);

        name = itemView.findViewById(R.id.text_name);
        email = itemView.findViewById(R.id.text_email);
        desc = itemView.findViewById(R.id.text_desc);
        book = itemView.findViewById(R.id.text_book);
        imageSlider = itemView.findViewById(R.id.imageView3);
    }
}}